What is the authenticity of the Hadith narrated in "Sunan Abi Dawud" concerning the Prophet's (peace be upon him) remission of the حد (prescribed punishment) for a man who apostatized from Islam, and how is it applied today if it is authentic and not abrogated?

The hadith mentioning the Prophet's (peace and blessings be upon him) initial refusal to pledge allegiance to Abdullah ibn Sa'd ibn Abi Sarh during the conquest of Mecca, and his subsequent acceptance after Uthman's intercession, is not evidence against the killing of an apostate. Abdullah deserved to be killed for two reasons: apostasy from Islam (which is a right of Allah that can be waived by repentance), and insulting the Prophet (peace and blessings be upon him) and slandering him (which is a right of the Prophet that can be waived by his forgiveness). The punishment for apostasy was waived by Abdullah's repentance and return to Islam, and the punishment for insult and slander was waived by the Prophet's (peace and blessings be upon him) forgiveness. Thereafter, Abdullah's Islam was good, as agreed upon by the statements of scholars. Sheikh al-Islam Ibn Taymiyyah emphasizes that the Prophet's initial refusal to pledge allegiance to him and his waiting for someone to kill him indicates the permissibility of killing one who slanders the Prophet, even if he comes repenting from his disbelief and slander, and that what preserved his life was the Prophet's (peace and blessings be upon him) forgiveness, not merely his embracing Islam.