After these things
"These things" refers to when the kings fought and Abram rescued Lot.
the word of Yahweh came to Abram in a vision, saying,
The idiom "the word of Yahweh came to" is used to introduce a special message from God. AT: "Yahweh gave a message to Abram in a vision. He said," or "Yahweh spoke this message to Abram in a vision:" (See: rc://en/ta/man/translate/figs-idiom)
shield ... reward
God used these two metaphors to tell Abram about his character and his relationship to Abram. (See: rc://en/ta/man/translate/figs-metaphor)
I am your shield
Soldiers use a shield to protect themselves from their enemies. AT: "I will protect you like shield" or "I am your shield to protect you" (See: rc://en/ta/man/translate/figs-metaphor)
"payment." This refers to the payment a person deserves. Two possible meanings are 1) "I am all that you need" or 2) "I will give you all you need."
Abram said, "Since you have given me
"Abram continued speaking and said, 'Since you have given me'"