What is the meaning of Meethaaq taken from the prophets (Anbiaa)?

Question

A Solemn pledge was taken from the prophets (Anbiaa) to believe in any Messenger (Rasool) coming after them (Verse 3:81). This pledge seems to be mentioned again in verse 33:7.
What is the exact significance of that pledge?
That Rasool (messenger) will recite the same verses which were given to the Nabi (a.s.) that every one will believe in that Rasool and will offer help to him. These are the words. Seems to be difficult to understand that a Rasool comes after a Nabi (prophet).

Answer 1

In verse 3:81 we learn that this pledge has been taken from the Prophets (Anbiya'), where they promise to believe and follow (and support) a (any) Messenger (Russul) that might come later (while they are alive) and in verse 33:7 it was taken from Prophets and Messengers too (including Muhammad). So at first sight there seem to be a difference.

About the meaning in 3:81

Allah states that He took a pledge from every Prophet whom He sent from Adam until `Isa, that when Allah gives them the Book and the Hikmah, thus acquiring whatever high grades they deserve, then a Messenger came afterwards, they would believe in and support him. Even though Allah has given the Prophets the knowledge and the prophethood, this fact should not make them refrain from following and supporting the Prophet who comes after them. (Tafsir ibn Kathir)

About 3:81 Imam al-Qurtoby said that most scholars say that this means that any Prophet (Naby) has confirmed and promised to support a Messenger (Rassul) if he'd be alive to do so. The Kufi's added that not only a Prophet but all his followers would follow and support a Messenger. He also quoted that ibn 'Abbas and 'Ali that "the Messenger" in this verse refers to Muhammad.

Sheikh Taher Benachour in his at-tahrir wa tanwir said this pledge was taken from all Prophets and it consists in ordering their followers to follow, believe and support a Messenger if they came confirming their message! The goal of this is informing their nation so that this pledge would be transmitted by generations. He also gave quotes from the Book of Deuteronomy (Musa asking Allah to send a Messenger out of the descendants of 'isma'ail) and Gospel of John ('Isa asking Allah to send somebody to confirm his message).

Note that this solemn pledge taken from all the Prophets emphasizes the importance of the message of Muhammad and pays a special tribute to it.

About the meaning in 33:7

Allah tells us about the five Mighty Messengers with strong resolve and the other Prophets, how He took a covenant from them to establish the religion of Allah and convey His Message, and to cooperate and support one another, ...
(And when Allah took the covenant of the Prophets, saying: "Take whatever I gave you from the Book and Hikmah, and afterwards there will come to you a Messenger confirming what is with you; you must, then, believe in him and help him.'' Allah said: "Do you agree, and will you take up My covenant'' They said: "We agree.'' He said: "Then bear witness; and I am with you among the witnesses.'') (3:81) This covenant was taken from them after their missions started. Elsewhere in the Qur'an, Allah mentions five by name, and these are the Mighty Messengers with strong resolve. They are also mentioned by name in this Ayah and in the Ayah (42:13)...
(And when We took from the Prophets their covenant, and from you, and from Nuh, Ibrahim, Musa, and 'Isa son of Maryam.) This Ayah begins with the last Prophet, as a token of respect, may the blessings of Allah be upon him, then the names of the other Prophets are given in order, may the blessings of Allah be upon them. Ibn 'Abbas said: "The strong covenant is Al-`Ahd (the covenant). (tafsir ibn Kathir)

Al-Qurtoby didn't add much to that expect that he quoted that the named Messengers were the five Mighty Messengers أولو العزم من الرسل (the Imams/leaders of the nations) and he added a hadith which is quoted in tafsir ibn Kathir (The translation above is summarized and maybe "cleaned") which has a weak narrator in the chain, to explain why Muhammad was named first :

وقدم محمدا في الذكر لما روى قتادة عن الحسن عن أبي هريرة أن رسول الله صلى الله عليه وسلم سئل عن قوله تعالى وإذ أخذنا من النبيين ميثاقهم ومنك ومن نوح قال : كنت أولهم في الخلق وآخرهم في البعث .

(My own translation of the quote take it with care) - - -

He began with Muhammad because of what is narrated by Qatadah from al-Hassan (al Basry) on the authority of abu Hurrairah: that the Messenger of Allah peace be upon him was asked about "And [mention, O Muhammad], when We took from the prophets their covenant and from you and from Noah ..." he said: I was the first being created and the last being sent.

He also added that part of this pledge was "to establish the religion and not be divided therein." as avoiding division is equal to avoiding following disbelievers.

Taher Benachour added that this verse is the beginning of the story of al-Ahzab, so the emphasis is on the pledge of supporting the religion or word of Allah which they have been sent with (in general and Islam in special) this means:

• saying and spreading the truth,
• spread what they have been ordered to without any fear nor (false) politeness towards disbelievers and munafiqeen,
• not to follow their desires and nafs,
• and not to leave aberrant and corrupt people doing their bad deedswithout interfering or guiding them,
• ...

if they did so Allah promised them success.

Conclusion

As you see on the whole both verses are equal to some extent, but maybe the emphasis and context play a role on making a slight difference on what exactly is meant in each of them.