Genesis 15:13-16 meaning

Verses 13-14 are a prophecy of the Egyptian bondage and Exodus after 400 years in slavery. Know for certain is the response to Abram's question in verse 8, "How may I know I will possess it?" God answers your descendants will be strangers in a land that is not theirs. God predicts Abram's descendants will dwell in a foreign land, other than the promised land of Israel. God even foretells the time frame, saying they will be enslaved and oppressed four hundred years. Abram's descendants would be slaves of the rulers in a foreign land (Egypt) for four centuries but would be released in "the fourth generation." The bondage in Egypt was certainly a part of God's overall plan. Not even 400 years of bondage could interfere with God's plan to fulfill the covenant.

I will also judge the nation whom they will serve, is a reference to the plagues inflicted upon Egypt ( Exodus 6:6, 7:4, 12:12). But afterward they will come out with many possessions. This promise was fulfilled at the time of the exodus from Egypt (Exodus 12:35-39; Psalm 105:37). The Egyptians gave many gifts to the Israelites upon their departure.

God reassures Abram that the foretold slavery in Egypt would not occur in his lifetime saying, you shall go to your fathers in peace. Abram was buried at a good old age of 175 (Genesis 25:7-8).

In the fourth generation they will return to the promised land does not contradict the "400 years" of verse 13. The word "generation" in Hebrew is the word Dor meaning a period or duration of time. In general, the word indicates the time from birth to death. However, it can also encompass the time from one's birth to the birth of one's first child; the living adults of a certain time or place; a time period as it is defined through major events, persons, behavior, or the spirit of an age. Figuratively, it is used to mean an indefinite or unending length of time. Therefore, 400 years could be four generations, particularly when considering the times of the patriarchs a person lived about a hundred years.

The Amorites sinned so much that they defiled the land and proved themselves no longer worthy to live upon it (Leviticus 18:24-27; Deuteronomy 9:4-5; Amos 2:9; 1 Kings 14:24). We know God was merciful, giving them more than four centuries to show a change of heart, as He says here the iniquity of the Amorite is not yet complete, So, Israel's deliverance would not come until the sin of the Amorites was complete. God later warned the Israelites that if they sin in the same manner, so as to defile the land, He would cast them out and give the land to other peoples (Joshua 23:11-13). God is merciful, but God is also righteous, and wickedness has consequences.