Which covenant he made with Abraham - Which he "ratified" with Abraham. Literally, "which he cut with Abraham." Genesis 17:2-14. Compare the notes at Psalm 50:5.
And his oath unto Isaac - Confirming the promise made to Abraham. See Genesis 26:2-5.

Which [covenant] he (e) made with Abraham, and his oath unto Isaac;
(e) The promise God made to Abraham to be his God, and the God of his seed after him, he renewed and repeated again to his seed after him.

Which covenant he made with Abraham,.... Or made it known unto him, and showed him his particular interest in it; promised that he would be his God, that he would bless him; and that in his seed, the Messiah, that should spring from him, all nations of the earth should be blessed, Genesis 12:2, compare with this Luke 1:72.
And his oath unto Isaac: he made known to Isaac the oath which he swore to Abraham, and promised to perform it, Genesis 26:3, or concerning Isaac (a); in whom his seed was to be called, and in whose line from him the Messiah was to come, the grand article of this covenant.
(a) de Isahac, Vatablus.

Which covenant--or, "Word" (Psalm 105:8).

Oath - Wherewith he ratified the covenant with Isaac, Genesis 26:3.