Rashi on Genesis 46:8/רש"י על בראשית מ״ו:ח׳

1הבאים מצרימה WHO CAME INTO EGYPT — Relative to that time when they were going to Egypt Scripture calls them “those who were coming” to Egypt (the participle) and one, therefore, need not be surprised that it does not state אשר באו “who came” (the perfect tense).