Charles Ellicott Commentary 2 Samuel 4:5

"And the sons of Rimmon the Beerothite, Rechab and Baanah, went, and came about the heat of the day to the house of Ish-bosheth, as he took his rest at noon." — 2 Samuel 4:5 (ASV)

Who lay on a bed at noon —according to the custom in hot countries of taking a siesta at midday. Ish-bosheth’s bed was, of course, in the coolest and most retired part of the house.