How authentic is the Hadith: "Ward off the prescribed punishments (Hudud) from Muslims as much as you can. If there is a way out for him, then let him go. For it is better for the Imam to err in forgiveness than to err in punishment"? And what is the meaning of Ibn Hajar's ruling on it as "gharib" (uncommon/strange) in "Muwafaqat al-Khabar al-Khabar" (1/444)?

This Hadith has an unauthentic chain of narration. The meaning of "gharaba" (strangeness) in Ibn Hajar's statement refers to one of the narrators being unique in transmitting it. Al-Tirmidhi narrated it in his Sunan with the same chain of narration, through Muhammad ibn Rabi'ah from Yazid ibn Ziyad al-Dimashqi, and he said: "We do not know of it being مرفوع (traced back to the Prophet) except from the Hadith of Muhammad ibn Rabi'ah from Yazid ibn Ziyad al-Dimashqi…" Waki' also narrated something similar from Yazid ibn Ziyad, but he did not elevate it (make it marfu'). Waki's narration is more authentic. Something similar to this has been narrated from more than one of the Companions of the Prophet (peace be upon him), who said likewise. Yazid ibn Ziyad al-Dimashqi is weak in Hadith. He was deemed weak by more than one Imam, such as Al-Bayhaqi and Al-Baghawi, and Al-Nasa'i said: "He is abandoned (matruk)." Ibn Hajar said in Al-Talkhis Al-Habir: "Waki' narrated it as mawquf (stopped at a Companion) from him, and that is more authentic. Al-Tirmidhi said so." Al-Albani declared the Hadith weak.