Is it permissible to perform Dhikr by saying: "My Lord is enough for me, glorified be Allah, there is nothing in my heart but Allah, the Light of Muhammad, peace be upon him," especially "the Light of Muhammad," and was this reported from the Prophet, peace be upon him?

Dhikr (remembrance of God) involves generating praise for Allah, sanctifying Him, glorifying Him, affirming His oneness, thanking Him, praising Him, exalting Him, and asking Him for the good of this world and the Hereafter. It is permissible to remember Allah with words not specifically transmitted from the Prophet (peace be upon him), provided that the dhikr includes praise for Allah or affirmation of His oneness, and does not imply any deficiency. As for the dhikr mentioned in the question ("There is nothing in my heart but Allah, the light of Muhammad"), it does not include praise for Allah or asking Him for His bounty, and it contains exaggeration in self-praise. Therefore, one should not worship through it. Goodness and virtue lie in following the adhkar (plural of dhikr) transmitted in the Qur’an and Sunnah (definition).