Musnad Abu Ya'la al-Mawsili 109:87

Narrated to us Mansur ibn Abi Muzahim, narrated to us Abd al-Rahman ibn Abi al-Mawal, from Muhammad ibn al-Munkadir, from Jabir, who said: The Messenger of Allah (may Allah bless him and grant him peace) used to teach us the *Istikhara* (seeking guidance) just as he used to teach us [the Quran], and he mentioned the [rest of the] hadith.