Jubilees 12.16ff

16 Abram dwelt with Terah his father in Haran two weeks of years. And in the sixth week, in the fifth year thereof, Abram sat up throughout the night on the new moon of the seventh month to observe the stars from the evening to the morning, in order to see what would be the character of the year with regard to the rains, and he was alone as he sat and observed. 17 And a word came into his heart and he said: All the signs of the stars, and the signs of the moon and of the sun are all in the hand of the Lord. Why do I search (them) out?
18 If He desires, He causes it to rain, morning and evening;
And if He desires, He withholds it,
And all things are in his hand.'
19 And he prayed that night and said,
'My God, God Most High, Thou alone art my God,
And Thee and Thy dominion have I chosen.
And Thou hast created all things,
And all things that are the work of thy hands.
20 Deliver me from the hands of evil spirits who have dominion over the thoughts of men's hearts,
And let them not lead me astray from Thee, my God.
And stablish Thou me and my seed for ever
That we go not astray from henceforth and for evermore.'

21 And he said, 'Shall I return unto Ur of the Chaldees who seek my face that I may return to them, am I to remain here in this place? The right path before Thee prosper it in the hands of Thy servant that he may fulfil (it) and that I may not walk in the deceitfulness of my heart, O my God.' 22 And he made an end of speaking and praying, and behold the word of the Lord was sent to him through me, saying: 'Get thee up from thy country, and from thy kindred and from the house of thy father unto a land which I will show thee, and I shall make thee a great and numerous nation.