Adam Clarke on Genesis 21:22

At that time - This may either refer to the transactions recorded in the preceding chapter, or to the time of Ishmael's marriage, but most probably to the former.

God is with thee - מימרא דיי meimera daiya, the Word of Jehovah; see before, Gen 15:1. That the Chaldee paraphrasts use this term, not for a word spoken, but in the same sense in which St. John uses the λογος του Θεου, the Word of God, (Joh 1:1), must be evident to every unprejudiced reader. See on Gen 15:1 (note).