Albert Barnes Commentary Psalms 63:7

"For thou hast been my help, And in the shadow of thy wings will I rejoice." — Psalms 63:7 (ASV)

Because thou hast been my help - Because you have interposed to defend me in danger. The idea is that he had experienced the divine interposition in times of danger, and that this was a reason why he should still confide in God. The argument is that God’s mercy and favor in the past is a reason why we should confide in him in time to come.

Therefore in the shadow of thy wings will I rejoice - Under the shadow or protection of your wings I will feel safe. See the notes at Psalm 17:8. Compare to Psalm 36:7; Psalms 57:1; Psalms 61:4.