Albert Barnes Commentary Luke 1:72

"To show mercy towards, our fathers, And to remember his holy covenant;" — Luke 1:72 (ASV)

To perform the mercy. To show the mercy promised. The expression in the original is, "To make mercy with our fathers"—that is, to show kindness to our fathers; and its appropriateness is founded on the fact that mercy to children is regarded as kindness to the parent. Blessing the children was blessing the nation; was fulfilling the promises made to the fathers, and showing that he regarded them in mercy.

His holy covenant. The word covenant means a compact or agreement. This is in use among human beings. It implies equality in the parties; freedom from constraint; freedom from previous obligation to do the thing now covenanted; and freedom from obligation to enter into a compact, unless a person chooses to do so. Such a transaction evidently can never take place between humankind and God, for they are not equal. Humankind is not at liberty to decline what God proposes, and is under obligation to do all that God commands. When the word covenant, therefore, is used in the Bible, it means sometimes a command; sometimes a promise; sometimes a regular law—as the covenant of the day and night; and sometimes the way in which God dispenses mercy—that is, by the old and new covenants. In the passage before us, it means the promise made to Abraham, as the following verses clearly show.