If he's not all-knowing or omniscient then prayer is just useless.
And also here's the verse:
Psalm 147:5
Great is our Lord and abundant in strength;
His understanding is infinite
Psalm 139:4
Even before there is a word on my tongue,
Behold, O Lord, You know it all.
Hebrews 4:13
And there is no creature hidden from His sight, but all things are open and laid bare to the eyes of Him with whom we have to do.
Psalm 139:1-3
For the choir director. A Psalm of David.
O Lord, You have searched me and known me. You know when I sit down and when I rise up; You understand my thought from afar. You scrutinize my path and my lying down, And are intimately acquainted with all my ways. Even before there is a word on my tongue, Behold, O Lord, You know it all.