Genesis 15 follows on from Genesis 14

I'm studying Genesis 15, in preparation for this Sunday's sermon.

Yet again Bruce Waltke is very helpful.

Here is one paragraph (from pages 239-240). The details he highlights probably won't make it into the sermon, unless they're crucial to the flow of thought in the chapter. But it's important that we see how the promises God makes Abraham in chapter 15 are precisely those that he needed after the events of chapter 14, redefining his protection, his reward and his allies.

The Lord’s claim for himself, ‘I am your shield’ (māgēn, 15:1), responds to Melchizedek’s description of God as the one ‘who delivered’ (miggēn, 14:20) Abraham’s enemies into his hand.
The Lord’s covenant (berîṯ, 15:18) takes the place of the Amorite allies (baʿalê ḇerĩṯ, lit. ‘owners of a covenant,’ 14:3).
‘Possessions’ in 15:14 (reḵuš) is the same word rendered ‘goods’ and ‘possessions’ in 14:11, 12, 16, 21. Abraham’s faithfulness is rewarded, not with tainted booty, but with God’s countless riches.