Rashi on Genesis 28:12/רש"י על בראשית כ״ח:י״ב

1עלים וירדים ASCENDING AND DESCENDING — It states first ascending and afterwards descending! Those angels who accompanied him in the land of Israel were not permitted to leave the Land: they ascended to Heaven and angels which were to minister outside the Land descended to accompany him (Genesis Rabbah 68:12).