How authentic is the Hadith: "Juhaynah are from me and I am from them; they become angry for my anger and are pleased for my pleasure; I become angry for their anger and am pleased for their pleasure; whoever angers them has angered me; and whoever angers me has angered Allah"?

The hadith, "Juhaynah is from me and I am from them...", was narrated by Al-Tabarani and Ibn Abi Asim, but its chain of transmission is weak because it contains Al-Harith bin Ma'bad, who is unknown, as mentioned by Al-Haythami and Al-Iraqi.

The more authentic narration is what Al-Bukhari and Muslim reported from the hadith of Abu Hurayrah that the Prophet (peace and blessings be upon him) said: "Quraysh, the Ansar, Juhaynah, Muzaynah, Aslam, Ashja', and Ghifar are my protectors/allies, they have no protector/ally besides Allah and His Messenger."

The Prophet (peace and blessings be upon him) described them as allies due to their faith and belief. Faith is the cause of alliance, as Allah the Almighty said: "Unquestionably, [for] the allies of Allah there will be no fear concerning them, nor will they grieve. Those who believed and were constantly conscious of Allah."