Psalms 77:15 - Clarke's commentary and critical notes on the Bible

Thou hast with thine arm redeemed thy people, the sons of Jacob and Joseph. Selah. The son. of Jacob and Joseph - "The sons which Jacob begat and Joseph nourished." says the Chaldee. The Israelites are properly called the sons of Joseph as well as of Jacob, seeing Ephraim and Manasseh, his sons, were taken into the number of the tribes. All the latter part of this Psalm refers to the deliverance of the Israelites from Egypt; and the psalmist uses this as an argument to excite the expectation of the captives. As God delivered our fathers from Egypt, so we may expect him to deliver us from Chaldea. It required his arm to do the former, and that arm is not shortened that it cannot save.