Is the supplication: "O Allah, O You who connect those who are cut off, connect us to You, and do not let others cut us off from You" authentic and narrated from the Prophet, may Allah's prayers and peace be upon him, or is it unauthentic?

This supplication has not been reported in the Sunnah, but there is nothing in Islamic law to prevent supplicating with it; its meanings are good and wholesome, and it contains an acknowledgment of one's need for Allah and a desire for His closeness and grace. The meaning of "O Uniter of those who are cut off, unite us with You" is to draw the servant closer to Allah through true servitude and to attain His pleasure and love. As for "and do not cut us off from You by others," it means that the heart should not be preoccupied with anything other than Allah the Almighty. There is no harm in supplicating with these words, but they should not be adopted as a regular litany like the established supplications.