תּלמוד אויף בראשית 17:2

HALAKHAH: Rebbi Yoḥanan bar Marya said, it is written: “On that day, the Eternal concluded a covenant with Abram as follows,” etc., up to “but my covenant I shall affirm with Isaac,” etc., thirteen covenants¹⁶⁰In Gen. 17:2–21 the word “covenant” appears 12 times. Therefore, Gen. 15:18 is added to reach the lucky number 13, the number of God’s attributes of mercy (Ex. 34:6–7) even though it speaks of a prior covenant; cf. the preceding Note..