Hello juvenissun,
Seeking intercession (tawassul) from the Prophet (sallallahu 'alayhi wa sallam) - and from other pious people whether alive or dead - is accepted by certain of the Muslims (especially the Shia) and rejected by others (especially the Salafī and the Qur’anists).
Those who reject tawassul claim that it is not permissible to call on the Prophet in prayer after his death, since prayer is an act of worship that can only be directed to Allāh (Subḥānahu ūta'āla) alone.
The following is quoted in support of this claim:
‘Who could be more wrong than a person who calls on those other than Allāh, those who will not answer him till the Day of Resurrection, those who are unaware of his prayers, those who, when all mankind is gathered, will become his enemies and disown his worship?’
(Al-Ahqaf: 5-6).
As far as the rejecters of tawassul are concerned, asking help from anyone other than Allāh (Subḥānahu ūta'āla) is not acceptable in Islam, and is a form of idolatry or polytheism.
The Salafī Shaykh Ibn ‘Uthaymeen writes:
‘If the intention is to call upon (Muhammad and others) and seek their help, then the person is a mushrik (one who associates partners with Allāh) in the sense of major shirk that puts one beyond the pale of Islam, and he must repent to Allāh and call upon Allāh alone, as Allāh says: ‘Is not He (better than your gods) Who responds to the distressed one, when he calls on Him, and Who removes the evil, and makes you inheritors of the earth, generations after generations? Is there any god with Allāh? Little is that you remember!’ (al-Naml: 62).
‘As well as being a mushrik, he is also fooling himself. Allāh says: ‘And who turns away from the religion of Abraham except him who befools himself?’ (Al-Baqarah: 130); (and again): ‘And who is more astray than one who calls on besides Allāh, such as will not answer him till the Day of Resurrection, and who are unaware of their calls to them?’ (Al-Ahqaf: 5).
(Fatawa al-Shaykh Ibn ‘Uthaymeen: 2-133).
The Salafī Shaykh Ibn Baaz writes:
‘Allāh has stated in His Holy Book and on the lips of His Messenger (peace and blessings of Allāh be upon him) that worship is the right of Allāh alone and no one else has any share of it, and that du’a is a kind of worship, so if a person says in any place on earth, Muhammad, help me, or save me, or support me, or heal me, or support your ummah, or heal the sick Muslims, and guide their misguided ones and so on, then he is making him a partner with Allāh in worship. The same applies to those who do the same thing with regard to other Prophets, angels…or any other created beings, because Allāh says: ‘And I (Allāh) created not the jinn and mankind except that they should worship Me (Alone)” (Al-Dhariyat: 56); (and): ‘O mankind! Worship your Lord (Allāh), Who created you and those who were before you so that you may become the pious.’ (Al-Baqarah: 21).
(Majmo’ al-Fatawa al-Shaykh Ibn Baaz: 2-453).
Rather than give the opinions of those who stand against the Salafī on this matter I refer you to the Salafī Imam and scholar of Hadith, Shaykh Muhammadad b. ‘Ali al-Shawkānī. He writes:
‘The second view is that tawassul through him (sallallahu 'alayhi wa sallam) may be performed in his life, and after his death, as well as in his presence and absence. It is not hidden to you that tawassul through him during his life is established, and tawassul through other than him after his death is also established by the consensus of the companions - a consensus of silent tacit approval (ijmā sukūtī)because none of them censured ‘Umar (Radi Allahu ‘anhu) for his Tawassul through al-‘Abbās (Radi Allahu ‘anhu).
‘Regarding what those who forbid tawassul to Allah through the Prophets and the saints cite to support their position, such as Allah's sayings: ‘We only worship them in order that they may bring us nearer’ (39:3); ‘Do not call on any other god with Allah, or you will be among those who will be punished" (26:213); ‘Say: Call on those besides Him whom ye fancy; they have no power to remove your trouble from you or to change them. Those unto whom they cry seek for themselves the means of approach to their Lord, which of them shall be the nearest; they hope for His mercy and fear His wrath: for the wrath of thy Lord is something to take heed of (17:57). These verses are irrelevant.
‘Rather: they support exactly the reverse of what the objectors to tawassul claim, since the verses are related to another issue. To wit: the verse ‘We only worship them in order that they may bring us nearer’ explicitly states that they worship them for that purpose, whereas the one who makes Tawassul through a scholar, for example, never worships him, but knows that he has a special distinction (maziyya) before Allah for being a carrier of knowledge; and that is why he uses him as a means.
‘Similarly irrelevant to the issue is Allah's saying: ‘Do not call on any other god with Allah.’ This verse forbids that one should call upon another together with Allah, as if saying: ‘O Allah and O So-and-so.’ However, the one who makes tawassul through a scholar, for example, never calls upon other than Allah. He only seeks a means to Him through the excellent works that one of His servants achieved, just as the three men in the cave who were blocked by the rock used their good works as a means to have their petition answered.
‘Similarly irrelevant to the issue is Allah's saying: ‘Those unto whom they cry...’ for it refers to people who call upon those who cannot fulfil their request, at the same time not calling upon Allah Who can; whereas one who makes tawassul through a scholar, for example, never called except upon Allah, and none other besides Him.
‘The above shows the reader that these objectors to tawassul are bringing forth evidence that is irrelevant to the issue at hand. Even more irrelevant is their citing of the verse: ‘The Day when no soul shall have power to do anything for another: for the Command that Day, will be all with Allah.’ (82:19) for that noble verse contains nothing more than the fact that Allah alone decides everything on the Day of Judgment, and that none other will have any say at that time. However, the maker of tawassul through one of the Prophets or one of the scholars, never believes that the one through whom he makes tawassul is in partnership with Allah on the Day of Judgment! Whoever believes such a thing in relation to a Prophet or non-Prophet is in manifest error.
‘Equally irrelevant is their objection to tawassul by citing the verses: ‘Not for you is the decision in the least’ (3:128); ‘Say: I have no power over good or harm to myself except as Allah wills’ (7:188) for these two verses are explicit in that the Prophet has no say in Allah's decision and that he has no power to benefit or harm himself in the least, let alone someone else: but there is nothing in those two verses to prevent tawassul through him or any other of the Prophets or Friends of Allah or scholars.
‘Allah has given His Prophet the Exalted Station (al-maqām al-maḥmūd) - the station of the Great Intercession (al-shafa`a al-`uzma), and He has instructed creation to ask for that station for him and to request his intercession, and He said to him: ‘Ask and you shall be granted what you asked! Intercede and you shall be granted what you interceded for!’ And in His Book He has made this dependence on the fact that there is no intercession except by His leave, and that none shall possess it except those whom He pleases...
‘Equally irrelevant is their adducing as proof against tawassul: ‘And admonish your nearest kinsmen’ (26:214) whereupon the Prophet said: "O So-and-so son of So-and-so, I do not have any guarantee on your behalf from Allah; and O So-and-so daughter of So-and-so, I do not have any guarantee on your behalf from Allah." For in the preceding there is nothing other than the plain declaration that hecannot benefit anyone for whom Allah has decreed harm, nor harm anyone for whom Allah has decreed benefit, and that he does not have any guarantee from Allah from any of his close relatives, let alone others. This is known to every Muslim. There is nothing in it, however, that prohibits making tawassul to Allah through the Prophet, for tawassul is a request from the One Who holds power to grant and deny all requests. The petitioner who makes tawassul only desires to place, at the front of his petition, what may be a cause for the granting of his petition by the One Who alone gives and withholds, the Owner of the Day of Judgment.
(Essay: al-Durr al-Nadid fi Ikhlas Kalimat al-Tawhid).
Almost Finally:
You will see that my Sister does not seek intercession from the Prophet (sallallahu 'alayhi wa sallam) because she does not think it right to do so. I honour her behaviour in this matter. I honour her because; having looked at all the arguments both for and against the practice, she has selected one view over the other, and is acting on her conscience. This is correct behaviour under Islam, and may Allāh (Subḥānahu ūta'āla) reward her for it.
Finally:
Shaykh Ibn Taymiyya, when speaking about the words of the Exalted: ‘You who believe, be mindful of Allāh, seek ways to come closer to Him and strive for His cause, so that you may prosper.’ (Al-Ma’ida:35) writes:
‘Seeking a means of approach to Allāh (Subḥānahu ūta'āla) is only achieved by the one who performs tawassul to Allah through his own faith in Muhammad and following him. This tawassul through faith in him and obedience to him is obligatory upon every single person and at every time, both internally and externally, both during his (sallallahu 'alayhi wa sallam’s) life and after his death, and in his presence and absence. Tawassul through faith in him and obedience to him is not lifted from anyone of the creation under any circumstance after the proof has been established upon him. This is not lifted with any excuse.
‘There is no way to achieve the Grace of Allah, His mercy, and salvation from His chastisement and punishment save by tawassul through him and obedience to him. He (sallallahu 'alayhi wa sallam) ) is the one who shall intercede for the creation, he is the possessor of the lofty station (al-maqām al-maḥmūd) whom the first and last envy over him. He is the greatest of the intercessors in stature, and the highest of them in rank with Allah………………………So, whoever the Messenger supplicates and intercedes for, he may perform tawassul to Allah through his intercession and supplication just as his companions performed tawassul to Allah through his supplication and intercession, and just as the people shall perform tawassul to Allah on the Day of Judgement through his (sallallahu 'alayhi wa sallam’s) supplication and intercession.’
(Ibn Taymiyya: ‘A Noble Principle Concerning Tawassul and Means’).
Have a good day.