Is it permissible in the funeral prayer to say, "O Allah, if he was among those who testified to Your Oneness and to Your Prophet’s prophethood, and died upon that," before supplicating for the deceased?

This specific wording, "O Allah, if he was among those who bore witness to Your Oneness and to Your Prophet's message, and died upon that," is not found in the authentic supplications transmitted from the Prophet (peace be upon him) or the righteous predecessors. Rather, in some supplications, it is affirmed for the Muslim that he bore witness that there is no god but Allah and that Muhammad is the Messenger of Allah, as in the supplication of Abu Hurayrah: "O Allah, he is Your servant, the son of Your servant, and the son of Your female servant. He bore witness that there is no god but You, and that Muhammad is Your servant and Your Messenger. And You are more knowledgeable about him. O Allah, if he was a doer of good, then increase his good deeds. And if he was a doer of evil, then overlook his evil deeds. O Allah, do not deprive us of his reward, and do not try us after him." One should limit oneself to the authentic supplications or those that convey a similar meaning.