A son of sharecroppers, he rose to the chairmanship of the House Oversight and Reform Committee, which gave him a towering perch from which to investigate President Trump. Mr. Cummings, 68, who died last week after a series of health challenges, was memorialized by congressional leaders in both parties as a man of faith and dignity, and a dedicated public servant, but also as a friend.

“Perhaps this place and this country would be better served with a few more unexpected friendships,” said a teary-eyed Representative Mark Meadows, the conservative North Carolina Republican whose close friendship with Mr. Cummings, despite their strong political differences, was well known in the Capitol. “I know I’ve been blessed by one.”