Albert Barnes Commentary 2 Samuel 3:35

"And all the people came to cause David to eat bread while it was yet day; but David sware, saying, God do so to me, and more also, if I taste bread, or aught else, till the sun be down." — 2 Samuel 3:35 (ASV)

To eat meat ... - Fasting was a sign of the deepest mourning (2 Samuel 1:12). The fast lasted until the sun had set.