Targum zu Bereschit 30:22

And the remembrance of Rahel came before the Lord, and the voice of her prayer was heard before Him; and He said in his Word that He would give her sons.

Four keys are held in the hand of the Lord of all the world, even the Lord, and He will not deliver them either to angel or to saraph; the key of the rain, the key of the provender, the key of the sepulchre, the key of barrenness. The key of rain : for thus the Scripture expoundeth, The Lord shall open unto thee His good treasure. The key of provender: for thus the Scripture expoundeth, Thou openest thine hand. The key of the sepulchre: for thus the Scripture expoundeth, When I shall open your sepulchre. The key of barrenness Scripture expoundeth, And Elohim remebered Rahel. And the Word of the Lord remembered Rahel in His good compassions, and the Word of the Lord heard the voice of her prayer, and He said in His Word that He would give her children.