Amen I say unto you, so it is in the Greek, a phrase, as some observe never used but by God and Christ himself; who is the Amen, the faithful and true witness, Revelation 3:14, though the servants of God have sometimes used it, as an adverb of wishing. It is by most concluded a form of an oath, God by it swearing by his truth and faithfulness. Till heaven and earth pass, & c.; that is, the law is the certain and unchangeable will of God concerning reasonable creatures, and it shall never be altered in the least tittle, nor ever be abolished; you may therefore be secure that I come into the world upon no such errand.
Related Commentaries of Matthew 5:18
Matthew 5:18
18 For verily I say unto you, Till heaven and earth pass, one jot or one tittle shall in no wise pass from the law, till all be fulfilled.