'Serving' in the Bible

Now Solomon was ruling over all the kingdoms from the River [to] the land of [the] Philistines, and up to the border of Egypt, who [were] bringing tribute and [were] serving Solomon all the days of his life.

Then King Rehoboam consulted with the old men who had been {serving} before Solomon his father when he was alive, saying, "How [are] you advising [me] {to answer this people}?"

But he rejected the advice of the old men, which they gave him, and he consulted with the youngsters who had grown up with him, who were {serving} before him.