A person asked Imam al-Sadiq (AS), 'I seek goodness from Allah when I want to do something but I am unable to make up my mind', so the Imam (AS) said to him, 'Open the Qur'an and look at the first verse that you see and act by it, Allah willing.'
Imam Ja'far ibn Muhammad al-Sadiq [as]
Tahdhib al-Ahkam, v. 3, p. 310, no. 960