1 Samuel 20:27

And it came to pass on the morrow, which was the second day of the month, that David's place was empty: and Saul said unto Jonathan his son, Wherefore cometh not the son of Jesse to meat, neither yesterday, nor to day?

On the morrow, which was the second day of the month. The time of the moon's appearance being uncertain, whether at mid-day, in the evening, or at midnight, the festival was extended over two days. Custom, not the law, had introduced this.

Saul said unto Jonathan ... Wherefore cometh not the son of Jesse? The question was asked, as it were, casually, and with as great an air of indifference as he could assume. And Jonathan having replied that David had asked and obtained his permission to attend a family anniversary at Beth-lehem, the pent-up passions of the king, who penetrated the prince's policy, burst out in a most violent storm of rage and invective against his son.