The word translated 'fulfill' in Matthew 5 is the root 'pleroo' in Greek.
In the Septuagint (Greek translation of the OT, from about 250 BC) the word 'pleroo' in Greek translates the Hebrew word 'malei'. It almost always means #8216;to fill #8217; But there are other nuances of the word.
Here is the Strongs#8217;s definition:
Matthew 5:17 as #8216;end, terminate#8217; is only one possible reading. I believe that the literary/cultural/historical context of this verse lends weight to tranlating 'pleroo' as #8216;confirm, authenticate#8217; and probably also #8216;do, keep.#8217;
Mishnah, AVOT 4:9
R. JONATHAN SAID: WHOEVER FULFILS (kum) THE TORAH OUT OF [A STATE OF] POVERTY, HIS END [WILL BE] TO FULFIL IT OUT OF [A STATE OF] WEALTH; AND WHOEVER DISCARDS THE TORAH OUT OF [A STATE OF] WEALTH, HIS END [WILL BE] TO DISCARD IT OUT OF [A STATE OF] POVERTY
Deuteronomy Rabbah 11:6
Halachah: When a Jew goes up to read the Law, he is not permitted to commence reading it before he has recited the blessings. First he must recite the blessings and then he reads. And thus Moses, when he had the privilege of receiving the Torah, first recited a blessing, and then he read it. R. Eleazar asked: What was the blessing which Moses recited before reading it? [It was], Blessed art Thou, O Lord, King of the Universe, who hast chosen this law and sanctified it and hast found pleasure in them who fulfil it. He did not say, ' in them that labour at it,' nor, ' in them who meditate in it,' but, ' in them that fulfil (kum) it,' that is to say, in them who carry out the words of the Torah.