Samuel's words were confirmed by Jehovah's sending thunder and rain (vv. 16-18). Samuel told them to stand and see the great thing that Jehovah would do before their eyes. Then he went on to say, "I will call to Jehovah, that He would send thunder and rain; and you will know and see that your wickedness which you have done in the sight of Jehovah by asking for a king for yourselves is great" (v. 17). Then Samuel called to Jehovah, and Jehovah sent thunder and rain on that day. These were not positive signs, for they were signs not of God's happiness but of His displeasure.
After Samuel called to Jehovah and He sent thunder and rain, all the people feared Jehovah and Samuel greatly (v. 18b).
Verses 19 through 25 record the people's confession of their sin and Samuel's charge to them and his praying for them.
The people confessed their sin, saying that they had added to all their sins the evil of asking for a king for themselves. Thus, they begged Samuel to pray to Jehovah his God that they would not die (v. 19).
Samuel charged the people of Israel not to turn away from following Jehovah but to serve Him with all their heart (v. 20). He warned them not to turn away to vain idols, which, being vanity, could not profit them or deliver them. The people needed to have only one heart, a heart that was toward God and with God. Therefore, Samuel said, "Only, fear Jehovah and serve Him in truth with all your heart, for consider what great things He has done for you. But if you still do wickedly, both you and your king will be consumed" (vv. 24-25).