Samuel was disappointed that the people had requested a human king to reign over them instead of God. “And Samuel said unto all Israel, Behold, I have hearkened unto your voice in all that ye said unto me, and have made a king over you. And now, behold, the king walketh before you: and I am old and grayheaded; and, behold, my sons are with you: and I have walked before you from my childhood unto this day.” (I Samuel 12:1-2) Samuel was old and tired and he called the people together and admonished them for their continual rebellion. After that, he prayed to God to show the rebellious people a special miracle, which God did.
“Is it not wheat harvest to day? I will call unto the LORD, and he shall send thunder and rain; that ye may perceive and see that your wickedness is great, which ye have done in the sight of the LORD, in asking you a king. So Samuel called unto the LORD; (I Samuel 12:17)
God’s Answer to Samuel
“and the LORD sent thunder and rain that day: and all the people greatly feared the LORD and Samuel. And all the people said unto Samuel, Pray for thy servants unto the LORD thy God, that we die not: for we have added unto all our sins this evil, to ask us a king.” (I Samuel 12:17-19)
It seems that God answered this prayer more for Samuel’s sake than for the people; proving to the people that God was with Samuel.