but you must wait seven days until I come to you and tell you what you are to do

1 Samuel 9:18-10:8

Saul answered, “But am I not a Benjamite, from the smallest tribe of Israel, and is not my clan the least of all the clans of the tribe of Benjamin? Why do you say such a thing to me?”

So the cook took up the thigh with what was on it and set it in front of Saul. Samuel said, “Here is what has been kept for you. Eat, because it was set aside for you for this occasion from the time I said, ‘I have invited guests.’” And Saul dined with Samuel that day.

Samuel said to Saul, “Tell the servant to go on ahead of us”—and the servant did so—“but you stay here for a while, so that I may give you a message from God.”

Then Samuel took a flask of olive oil and poured it on Saul’s head and kissed him, saying, “Has not the Lord anointed you ruler over his inheritance?  When you leave me today, you will meet two men near Rachel’s tomb, at Zelzah on the border of Benjamin. They will say to you, ‘The donkeys you set out to look for have been found. And now your father has stopped thinking about them and is worried about you. He is asking, “What shall I do about my son?”’

The Spirit of the Lord will come powerfully upon you, and you will prophesy with them; and you will be changed into a different person. Once these signs are fulfilled, do whatever your hand finds to do, for God is with you.

Go down ahead of me to Gilgal. I will surely come down to you to sacrifice burnt offerings and fellowship offerings, but you must wait seven days until I come to you and tell you what you are to do.”

Why?

Everything happened as Samuel told Saul, that the Lord had arranged it. Only one thing asked Saul to wait for Samuel seven days until Samuel came to you and tell him what Saul to do.

The Lord gives us power, ability, and freedom, but more important is to listen to the word of the Lord, such as Saul had to listen to the word of Samuel, but he didn't later.

Saul was full of the Holy Spirit and prophesied with others, then Saul was changed into a different person, the God is with Saul.

How?

When God is with us we may be full of the Holy Spirit. And the right of the Holy Spirit is in the hands of the Lord

Somehow we will make decisions on our own ideas, even if it is not a bad idea but more important is to trust in the Lord and obey his command with our heart and mind.