#It came about at that time

This phrase is used here to mark the beginning of a new part of the story. If your language has a way for doing this, you could consider using it here. (See: [[:en:ta:vol2:translate:writing_newevent]])

#Phicol

This is the name of a man. (See: [[:en:ta:vol1:translate:translate_names]])

#captain of his army

"commander of his army" (UDB)

#his army

The word "his" refers to Abimelech.

#God is with you in all that you do

Here the phrase "is with you" is an idiom that means God helps or blesses Abraham. AT: "God blesses everything you do" (See: [[:en:ta:vol1:translate:figs_idiom]])

#Now therefore

Here "Now" does not mean "at this moment," but is used to draw attention to the important point that follows. AT: "Therefore"

#swear to me here by God

The term "swear by" means to use the name of something or someone as the basis or power on which the oath is made. AT: "promise me with God as your witness"

#that you will not deal falsely with me

"that you will not lie to me"

#will not deal falsely ... nor with ... nor with

This can be stated in positive form. AT: "will deal honestly ... and with ... and with"

#Show to me ... covenant faithfulness that I have shown to you

The two men had made a covenant with each other. The abstract noun "faithfulness" can be stated as "faithful" or "loyal." AT: "Be to me ... as faithful as I have been to you" (See: [[:en:ta:vol2:translate:figs_abstractnouns]])

#to the land

Here "land" stands for the people. AT: "to the people of the land" (See: [[:en:ta:vol2:translate:figs_metonymy]])

#I swear

This can be stated with the understood information. AT: "I swear to be as faithful to you and your people as you have been to me" (See: [[:en:ta:vol2:translate:figs_ellipsis]])