Rashi on Deuteronomy 32:9/רש"י על דברים ל״ב:ט׳

1כי חלק ה' עמו FOR THE PORTION OF THE LORD, HIS PEOPLE — Why all this? (Why did He save them from destruction?) because His portion was comprised in them and was destined to come forth. And who is His portion? עמו HIS PEOPLE. And Who is His people?

2יעקב חבל נחלתו JACOB THE ROPE OF HIS INHERITANCE — and he is the third amongst the patriarchs, who is endowed with three merits: the merit of his grandfather, the merit of his father and his own merit thus altogether three — like a rope (חבל) that is made up of three strands. Only he and his sons became His inheritance, not, however, Ishmael, Abraham’s son, nor Esau, Isaac’s son (cf. Sifrei Devarim 312:3),