#Isaac made a feast for them, and they ate and drank

Eating a meal together was a part of making the covenant with one another. (See: [[:en:ta:vol1:translate:figs_explicit]])

#for them

Here "them" refers to "Abimelech, Ahuzzath, and Phicol"

#they ate

Here "they" refers to Isaac, Abimelech, Ahuzzath, and Phicol. AT: "they all ate" (UDB)

#They rose early

"They awoke early"