How does a person know that God has accepted his deed, taking into account His saying, the Most High: "Indeed, Allah only accepts from the righteous"?

His (the Almighty's) saying: "Indeed, Allah only accepts from the righteous [who fear Him]" means that Allah accepts the deed in which the servant feared his Lord and performed it perfectly, fulfilling its conditions of faith, sincerity, and adherence to the Prophet, peace and blessings be upon him, even if the servant is disobedient in other matters. The acceptance of a deed is purely a grace from Allah, and the sign of its acceptance is that it bears fruit in other acts of obedience, and that the servant belittles and underestimates his own deed.