||[God] said to Abram, 'Know for sure that your descendants will be foreigners in a land that is not theirs for 400 years. They will be enslaved and oppressed.
Vayomer le-Avram yadoa teda ki-ger yihyeh zar'acha be'erets lo lahem va'avadum ve'inu otam arba me'ot shanah.
This occurs at the end of the verse, but from context, it belongs here. The 400 years were counted from Isaac's birth, since he never lived in his own land. It lasted until the Exodus (Seder Olam Rabbah; Rashi).
|They will be...|
Literally, 'they (the others) will enslave and oppress them.'