Mat 5:1

Mat 5-7: The proclamation: manifesto of the King. Christ’s self-portrait to challenge listener and reader.

HE WENT UP ON A MOUNTAINSIDE AND SAT DOWN: Moses received the Law standing before God, and descended from the mount to deliver it to the people. The One who is greater than Moses is seated, and delivers the Law in the mount as the very voice of God (TM 25).

Instances of Jesus withdrawing into a mountain, apart — sometimes for privacy and prayer, and sometimes to instruct his followers: Mat 5:1; 8:1; 14:23; 15:29; 17:1; 24:3; 28:16; Mark 3:13; 6:46; 9:2; 13:3; Luke 6:12; 9:28; 22:39; John 6:3,15; 8:1.

In addition, the whole of Mat 5-7 proves to be an extended commentary on Psalm 15:

A comparison of Psa 15 and the Sermon on the Mount (Matthew 5-7):