Albert Barnes Commentary Psalms 119:57

"Jehovah is my portion: I have said that I would observe thy words." — Psalms 119:57 (ASV)

Thou art my portion, O Lord - This begins a new division of the psalm, indicated by the Hebrew letter Cheth (ח ch), which may be represented in English by “ch.” On the meaning of the language here, see the notes at (Psalms 16:5). God was to him what other people seek in wealth, honor, pleasure, fame. To him, God was all and in all. He asked nothing else.

I have said - I have formed the purpose, and have expressed it. It is the deliberate and settled design of my life.

That I would keep thy words - That I would obey you at all times; that I would keep all your commandments.