1 Chronicles 5:20 NKJV
And they were helped against them, and the Hagrites were delivered into their hand, and all who were with them, for they cried out to God in the battle. He heeded their prayer, because they put their trust in Him.
The descendants of Reuben, the Gadites and half of the tribe of Manasseh went to war and were successful. 1 Chronicles 5:20 explained why. They prayed to God. They put their trust in Him. Prayers of petition must be made to God in faith. That is only possible when we trust in Him. In order to establish trust in God we must get to know Him. In order to get to know Him we must do several things. We must fellowship with Him through worship and meditation on His Word. Then we must step out on His Word and do as He says. If we practice these things our relationship with God will grow and we will learn to trust Him more and more. Then it will be easier to pray in faith and get results.