Rashi on Genesis 31:13/רש"י על בראשית ל״א:י״ג

1האל בית אל is the same as אל בית אל the ה of האל being redundant. It is customary for Scripture to speak thus, e. g. (Numbers 34:2) “When ye come into the land of Canaan הארץ כנען (instead of ארץ כנען).

2משחת שם WHERE THOU ANOINTEDST [A PILLAR] — This denotes distinction and eminence just as when one is anointed king one is raised to eminence: thus, too (Genesis 28:18) “and he poured oil upon the top of it (the stone)” that it might be anointed to be an altar (thus being distinguished among other stones).

3אשר נדרת לי WHERE THOU VOWEDST A VOW UNTO ME —and you are bound to fulfill it, for you said (Genesis 28:22) “it shall be God’s house”, signifying that you would offer sacrifice there.