2 Samuel 7:26-29

2 Samuel 7:26-29.And let thy name be magnified for ever, saying, The LORD of hosts is the God over Israel: and let the house of thy servant David be established before thee. For thou, O LORD of hosts, God of Israel, hast revealed to thy servant, saying, I will build thee an house: therefore hath thy servant found in his heart to pray this prayer unto thee. And now, O lord GOD, thou art that God, and thy words be true, and thou hast promised this goodness unto thy servant: Therefore now let it please thee to bless the house of thy servant, that it may continue for ever before thee:

You see how he clings to God’s promise: "Thou hast promised this goodness unto thy servant." If you get a promise from the Lord, and cling to it as you wrestle with the angel, you will surely prevail. You must win the blessing if you can plead, as David did, "Thou hast promised this goodness unto thy servant."