Matthew Poole and continuators on Genesis 15:13

13. And he said unto Abram, Know of a surety that thy seed shall be a stranger in a land that is not theirs , and shall serve them, and they shall afflict them four hundred years .

(i. e.) In Canaan and Egypt: for though Canaan was theirs by promise, to be fulfilled in after times, yet it was not theirs by actual donation and possession, but they were strangers in it, Gen, 17. 8. Psal. 105. 11, 12.

Exactly 405 years, but a small sum is commonly neglected in a great number, both in sacred and prophane writers. There were 430 years between the first promise, or between the renewing and confirming of the promise by the gift of Isaac and Israels going out of Egypt, or God's giving of the Law. Exod. 12. 40. Gal. 3. 17. but part of this time Abraham with his Son Isaac lived in much honour and comfort: but after Isaac grew up, the affliction here mentioned began with Isaac in Canaan, and continued to him and his posterity in Egypt, till this time was expired.

Marginal references: Act. 7. 6.; Exo. 1. 11.