Bay’ah means oath, allegiance and covenant (Al-Munjid in Urdu).
Surely Allah is satisfied with the believers who pledged allegiance to you (i.e. on the hands of the Prophet) under the tree….'(Surah Fath, Verse 18)
After Usman the people of Medina and its outskirts gathered in numbers at the doorstep of Hazrat Ali (a.s.). They all took the oath of complete obedience to him. They pledged their unconditional allegiance at his hands, when he stated that
‘I have a right upon you and you have a right upon me. And your right is that I be attentive towards your wellbeing and give you your complete entitlement from the public treasury, that I teach you so that you may no longer remain ignorant and train you in the manner in which you style your life…. And my right upon you is that you fulfill (the conditions and duties of) your pledge and guard my interests either before me or behind my back. When I beckon you, you should respond to my call and when I order something, obey it.”(Nahjul Balagha)
The third era is when Imam Hasan (a.s.) was sitting with some people, while the Amir of Syria, Muawiya, entered. Some people pledged allegiance at his hands, at which Imam (a.s.) remarked,’Do you not know that verily I am your Imam whose obedience is obligatory upon you (i.e. bay’ah is fundamental in Islamic law whose fulfillment is obligatory upon you. And you leave that for pledging your fealty to some other).'(Kamaaluddin vol 1, p. 316, chap. 29, tradition 2).
The companions of the Qaem (may Allah hasten his reappearance) will take a covenant (Bay’atn)at his hands that we will:
1. Not steal.
2. Not commit adultery.
3. Not abuse a Muslim.
4. Not murder anyone unlawfully.
5. Not violate anyone’s honor.
6. Not attack anybody’s dwelling.
7. Not harm anybody.
8. Not hoard gold, silver, wheat and barley.
9. Not usurp the property of the orphan.
10. Not give false testimony.
11. Not forsake the mosque.
12. Not drink wines and intoxicants.
13. Not wear clothes made of silk or golden thread.
14. Not wear a golden belt.
15. Not indulge in robbery.
16. Not attack travelers and wayfarers.
17. Not indulge in homosexuality.
18. Not destroy food stocks like wheat and barley.
19. Be contented with less.
20. Use perfumes and fragrances.
21. Stay away from uncleanness.
22. Exhort towards goodness.
23. Keep away from prohibited acts.
24. Wear coarse cloth.
25. Rest on an earthen pillow.
26. Strive in the way of Allah as is the right to do so.
And Imam (a.s.) will promise them that
1. He will stay with them.
2. He will dress like them.
3. He will keep a mount similar to theirs.
4. He will work according to their will.
5. He will stay contented with a little.
6. He will, with Allah’s aid, fill the earth with equity and justice as it would be filled with oppression and tyranny.
7. He will worship Allah as is the right of worship.
8. He will not post a guard or sentry for himself.
(Kitabe Jahan b’ad az-Zuhur, p. 125-126)