Rashi on Genesis 33:17/רש"י על בראשית ל״ג:י״ז

1ויבן לו בית AND HE BUILT FOR HIMSELF A HOUSE — He stayed there eighteen months — summer, winter and summer again (Megillah 17a); for the first mention of Succoth (booths which are erected for the cattle) points to the summer (when booths are necessary for the cattle), the mention of building a house to the winter, and the second mention of booths to the next summer.