We have many illustrations in the Bible where someone is praying and God withholds judgement or people praying and God bringing rain in answer to their prayers. For Christians we know that "...The effectual fervent prayer of a righteous man availeth much."-James 5:16 KJV
God hears and answers prayer. In fact, we are told to pray without ceasing.
"Pray without ceasing" - 1st Thessalonians 5:17 KJV
We know that God hears our prayers.
God is sovereign, but He works through means. God saves sovereignly but not apart from faith.
God sanctifies sovereignty, but not apart from obedience. God acts sovereignly, but not apart from prayer. So God has ordained means by which His sovereignty operates.
If you don’t believe, you will not be saved. If you don’t obey, you will not be sanctified. If you don’t pray, you won’t see the hand of God.
God ties His sovereign operation to the means, and prayer is the means He has chosen.