I'm not Rocky, but if you are looking for Scripture, verses such as Luke 3:16 are often considered to allude to it.
John answered and said to them all, "As for me, I baptize you with water; but One is coming who is mightier than I, and I am not fit to untie the thong of His sandals; He will baptize you with the Holy Spirit and fire.
Pentecostals often take the events of Pentecost itself as evidence. It is usually assumed by Pentecostals that all of the converts who are baptized and speak in tongues throughout Acts are also evidence. This is the reason some say that speaking in tongues is a necessary evidence, but I disagree on that point.
Of course, different churches will teach differently on this. As I said, I expect you to get different opinions.
I prefer to consider such passages as Eph. 5
18 And do not get drunk with wine, for that is dissipation, but be filled with the Spirit,
19 speaking to one another in psalms and hymns and spiritual songs, singing and making melody with your heart to the Lord ;