What is the meaning of "pledge allegiance" (al-mubaya'ah) in the hadith: "So when you see him, pledge allegiance to him, even if you have to crawl over snow, for he is the Caliph of Allah, the Mahdi"?

Linguistically, bay'ah (allegiance) means pledging obedience and striking a deal, as in the Almighty's saying: "Indeed, those who pledge allegiance to you are actually pledging allegiance to Allah," and the Prophet's (peace be upon him) saying to Mujashi': "Upon Islam and Jihad." It signifies a contract and an agreement.

From a technical perspective, Ibn Khaldun defined it as a covenant of obedience, whereby the one pledging allegiance promises their leader submission in matters concerning themselves and the Muslims, and obedience in what they are entrusted with. It used to be accompanied by a handshake to affirm the covenant, thus resembling the act of a seller and a buyer.

In "Tuhfat al-Ahwadhi," it is stated: "Al-Mubaya'ah (the act of pledging allegiance) is an expression of covenant, likened to a financial exchange, as in the Almighty's saying: 'Indeed, Allah has purchased from the believers their lives and their properties [in exchange] for that they will have Paradise.'"