The beginning of barley harvest. — This was immediately after the Passover (Leviticus 23:10-11), and therefore about the middle of April. The rains of autumn began in October, so that Rizpah’s watch must have been about six months. She spread the sackcloth as a tent to form a rough shelter during the long watch. For water dropped read water poured, the word being used for melting, flowing, and hence for heavy rain. It was not until these rains began (which may probably have been somewhat earlier than usual) that the people were assured of the Divine forgiveness, and therefore the bodies of the executed were left unburied until then.
Related Commentaries of 2 Samuel 21:9
2 Samuel 21:9
9 And he delivered them into the hands of the Gibeonites, and they hanged them in the hill before the LORD: and they fell all seven together, and were put to death in the days of harvest, in the first days, in the beginning of barley harvest.