# Then, behold

The word "behold" emphasizes the fact that the word of Yahweh came to Abraham again.

# the word of Yahweh came to him, saying, "This

"Yahweh gave him a message. He said, 'This" or "Yahweh spoke this message to him: 'This"

# This man

This refers to Eliezer of Damascus.

# the one who will come from your own body

"the one that you will father" or "your very own son." Abram's own son would become his heir.