"during his father [Abraham](rc://en/tw/dict/bible/names/abraham)'s lifetime" or "when [Abraham](rc://en/tw/dict/bible/names/abraham), his father, was living"
This was the reason that Isaac dug them out. Possible ways to translate this are: 1) Since this happened first, this sentence can come before the sentence about Isaac digging them out, as in the UDB. or 2) This sentence can start with "Isaac did this because the Philistines had stopped them up." (See: [[rc://en/ta/man/translate/figs-events]])