And it came to pass in the morning, when the meat offering was offered, that, behold, there came water by the way of Edom, and the country was filled with water.

Wesley's Notes

3:20 The meal - offering - That is, the morning sacrifice: which doubtless was attended with the solemn prayers of God's people. At this time Elisha joined his prayers with the prayers of God's people, especially those at Jerusalem. And this time God chose to answer their prayers, and to work this miracle, that thereby he might determine the controversy between the Israelites and the Jews, about the place and manner of worship, and give a publick testimony from heaven for the Jews, and against the Israelites. God that commands all the waters both above and beneath the firmament, sent them abundance of water on a sudden.

Jamieson-Fausset-Brown Bible Commentary

20-24. when the meat offering was offered-that is, at the time of the morning sacrifice, accompanied, doubtless, with solemn prayers; and these led, it may be, by Elisha on this occasion, as on a similar one by Elijah (1Ki 18:36).

behold, there came water by the way of Edom-Far from the Israelitish camp, in the eastern mountains of Edom, a great fall of rain, a kind of cloudburst, took place, by which the wady was at once filled, but they saw neither the wind nor the rains. The divine interposition was shown by introducing the laws of nature to the determined end in the predetermined way [Keil]. It brought not only aid to the Israelitish army in their distress, by a plentiful supply of water, but destruction on the Moabites, who, perceiving the water, under the refulgent rays of the morning sun, red like blood, concluded the confederate kings had quarrelled and deluged the field with their mutual slaughter; so that, rushing to their camp in full expectation of great spoil, they were met by the Israelites, who, prepared for battle, fought and pursued them. Their country was laid waste in the way, which has always been considered the greatest desolation in the East (2Ki 3:24).

Matthew Henry's Concise Commentary

3:20-27 It is a blessing to be favoured with the company of those who have power with God, and can prevail by their prayers. A kingdom may be upheld and prosper, in consequence of the fervent prayers of those who are dear to God. May we place our highest regard upon such as are most precious in his account. When sinners are saying Peace, peace, destruction comes upon them: despair will follow their mad presumption. In Satan's service and at his suggestion, such horrid deeds have been done, as cause the natural feelings of the heart to shudder; like the king of Moab's sacrificing his son. It is well not to urge the worst of men to extremities; we should rather leave them to the judgment of God.