How authentic is the attribution of this saying to Imam Al-Sadiq (peace be upon him): "Allah, the Almighty, revealed to Moses (peace be upon him): 'O Moses! Thank Me as I deserve to be thanked.' So he said: 'O Lord! How can I thank You as You deserve to be thanked, when there is no gratitude with which I thank You except that You have bestowed it upon me?' He said: 'O Moses! Now you have thanked Me, when you realized that it is from Me'"?

The aforementioned narration attributed to Ja'far al-Sadiq - may Allah have mercy on him - has not been authentically reported in Sunni texts with that exact wording. However, it has been narrated in various instances that Musa (Moses) - upon him be peace - asked his Lord about how to show gratitude for His blessings. The answer was that gratitude is shown by acknowledging that all blessings come from Him, or by recognizing that even the least blessing cannot be fully repaid by all of one's deeds, or by remembering Him frequently. So, if one remembers Him often, they have shown gratitude, and if they forget Him, they have shown ingratitude. A similar narration has been reported from Dawud (David) - upon him be peace.