من لا يحضره الفقيه, volume 1, page 563

Hadith.1553 - Hammad ibn Uthman al-Naab narrated from Him (as) that He said: "For istikhara (seeking divine guidance), a person should seek guidance from Allah (swt) during the last prostration (sajdah) of the two rak'ahs of Fajr prayer by repeating it one hundred and one times, praising Allah (swt), and sending blessings upon the Prophet and his family. Then, seek guidance from Allah (swt) fifty times, praise Allah (swt) again, and send blessings upon the Prophet and his family until completing the count of one hundred and one."

Translation: Bab Ul Qaim Publications — attributed by Thaqalayn·The Arabic above is the original.

Hadith.1554 - Hammad ibn Isa narrated from Najiyah, from Imam Jafar ibn Muhammad Al-Sadiq (as) that "Whenever He (as) intended to purchase a servant, an animal, or a light matter, or something of little importance, he would perform istikhara (seek Allah’s (swt) guidance) seven times. But if it was a serious matter, he would perform istikhara one hundred times”.

Translation: Bab Ul Qaim Publications — attributed by Thaqalayn·The Arabic above is the original.

Hadith.1555 - Mu'awiya ibn Maythara narrated that Imam (as) said: "No servant who performs istikhara (seeks Allah’s (swt) guidance) seventy times with this istikhara will be left without Allah (swt), the Mighty and Majestic, granting him guidance." The supplication is: "O’ the best of those who see, O’ the most hearing of the hearers, O’ the swiftest of reckoners, O’ the most merciful of the merciful, O’ the wisest of judges, send blessings upon Muhammad and his family and guide me in such and such matter."

Translation: Bab Ul Qaim Publications — attributed by Thaqalayn·The Arabic above is the original.