Jacob vowed a vow, i.e. bound himself by a solemn promise or obligation. Compare Genesis 14:22 Ecclesiastes 5:4. If God will be with me. He speaks not thus as if he doubted of the truth of God's promises, or would, like a mercenary person, make a bargain with God, but rather supposeth that God will do this for him, as he had in effect promised, Genesis 28:15, and thereupon obligeth himself to a grateful return to God for this mercy: If God will be with me, & c., as he hath just now assured me he will; or, Seeing God will be with me, & c., for the Hebrew im doth not always imply a doubt, but rather a supposition, and is oft rendered seeing that, as Exodus 20:25 Numbers 36:4 1 Samuel 15:17 Amos 7:2. And so the Greek particle answering to the Hebrew im is used, Matthew 6:22 Luke 11:34. Bread; food convenient, as it is called, Proverbs 30:8, which is oft signified by the name of bread. See Genesis 3:19.
Related Commentaries of Genesis 28:20
Genesis 28:20
20 And Jacob vowed a vow, saying, If God will be with me, and will keep me in this way that I go, and will give me bread to eat, and raiment to put on,