Sayyiduna Ghalib bin Abdullah bin Abjar (may Allah be pleased with him) narrates: I mentioned (the tribe of) Qays in the presence of the Messenger of Allah (peace and blessings be upon him), and the Prophet (peace and blessings be upon him) said: "May Allah have mercy on Qays, may Allah have mercy on Qays." It was said: "O Messenger of Allah, you are praying for mercy upon Qays?" He (peace and blessings be upon him) said: "Yes, they were upon the religion of my forefather Isma'il bin Ibrahim, the Friend of Allah (peace be upon them both). O Qays, greet Yemen; O Yemen, greet Qays. Indeed, Qays are the horsemen of Allah on the earth. By the One in Whose Hand is my soul, a time will surely come upon the people when this religion will have no helper except Qays. Indeed, Allah has horsemen from the people of the heavens who are marked, and horsemen from the people of the earth who are well known, and the horsemen of Allah from the people of the earth are Qays. Qays is but an egg that has hatched from us, the people of the household. Indeed, Qays are the dirra' of Allah", that is, the lions of Allah.
Imam al-Tabarani (may Allah have mercy on him) said: "This hadith is narrated from Ghalib bin Abjar only with this chain, and Qutaybah is alone in narrating it."
Hadith Referenceالمعجم الأوسط / باب الميم / 8015
Hadith Takhrij«أخرجه الطبراني فى «الكبير» برقم: 663»