The lepers began to think that if they kept this important matter secret during the whole night for their own private advantage, when the morning came they would be found out, accused, and punished (see margin).
Related Commentaries of 2 Kings 7:9
2 Kings 7:9
9 Then they said one to another, We do not well: this day is a day of good tidings, and we hold our peace: if we tarry till the morning light, some mischief will come upon us: now therefore come, that we may go and tell the king's household.