dear sheik,for research purpose i want you to provide me the Ahnaaf evidence for saying that if one catch the imam in tashahhud in jumuah prayer he needs to offer 2 raka'ah only.

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.

Imaam Abu Haneefah and his companion (prominent student) Abu Yoosuf viewed that the person who catches up with the Imaam in the Tashahhud of Jumu‘ah (Friday prayer) should complete it as Jumu‘ah. However, his companion Muhammad ibn Al-Hasan said that he should complete it as Thuhr (noon prayer). As-Sarakhsi stated both opinions along with their evidences in his book Al-Mabsoot, saying: "According to Imaam Abu Haneefah and Abu Yoosuf  if one catches up with the Imaam in the Tashahhud of Jumu‘ah or in its two prostrations of forgetfulness and followed him, then he has caught up the Jumu‘ah and should complete it two Rak‘ahs. However, Muhammad said: In this case one should pray four Rak‘ahs; for the Prophet, sallallaahu ‘alayhi wa sallam, said: "Whoever catches up with one Rak’ah of Jumu’ah with the Imaam, then he has caught up with the prayer; and if he catches up with only the sitting [Tashahhud], then he is to pray four Rak‘ahs." On the other hand, they (Abu Haneefah and Abu Yoosuf) have based their opinion on the saying of the Prophet, sallallaahu ‘alayhi wa sallam: “Whatever you catch up with (i.e. with the Imaam in congregation), pray, and whatever you have missed, make it up,” and he has missed two Rak‘ahs. Also, when he catches up with Tashahhud, he has caught up with the prayer because he has the intention (to offer Jumu'ah) other than the intention of offering Thuhr; so if he has the intention of Thuhr, then his joining the prayer behind him will not be valid." [End quote]

Thus, those who view that one should complete it as Jumu‘ah based their opinion on the following two matters:

Firstly, the statement of the Prophet, sallallaahu ‘alayhi wa sallam: "Whatever you catch up with (i.e. with the Imaam in congregation),  pray, and whatever you have missed, make it up.”

Secondly, he has caught up with a part of Jumu'ah and intended to offer it as Jumu‘ah and thus he should offer it as Jumu‘ah.

However, the majority of the scholars hold the opinion that whoever does not catch up with one Rak’ah of Jumu’ah with the Imaam, then he has missed the prayer and should complete it as Thuhr. Ibn Qudaamah said in Al-Mughni: "Most scholars are of the view that if one catches up with one Rak’ah of Jumu’ah along with the Imaam, he has caught it up and is to add another one to it and this will be valid for him. This opinion was adopted by Ibn Mas‘ood, Ibn ‘Umar, Anas, Sa‘eed ibn Al-Musayyib, Al-Hasan, ‘Alqamah, Al-Aswad, ‘Urwah, Az-Zuhari, An-Nakha‘i, Maalik, Ath-Thawri, Ash-Shaafi‘i, Is-haaq, Abu Thawr and As-haab Ar-Ra‘i (i.e. the Hanafis)... As to the one who catches up with less than one Rak‘ah, then he has missed Jumu‘ah prayer and should offer Thuhr prayer and it is the opinion of all those whom we have mentioned previously. On the other hand, Al-Hakam, Hammaad and Abu Haneefah said that one catches up with Jumu‘ah prayer if he catches up with any part of it with the Imaam. That is because the one who is obliged to complete what he has prayed with  the Imaam if he catches up with only one Rak‘ah, should do the same if he catches up with less than that as in the case of a traveler who prays behind a resident. Also, he has caught a part of the (Jumu'ah) prayer and thus he has caught up with it in the same manner he catches up with the Thuhr prayer. As for the statement of the Prophet, sallallaahu ‘alayhi wa sallam: "Whoever catches up with one Rak’ah of Jumu’ah, then he has caught up with the prayer", it means (i.e. by the understood divergent meaning which is not explicitly stated) that if he catches up with less than that, he has missed it. Also, because it is the opinion of the Companions and their followers whom we have stated earlier and no one opposed them during their time and thus it is a consensus. Bishr ibn Mu‘aath Az-Zayyaat reported from Az-Zuhri from Abu Salamah that the Prophet, sallallaahu ‘alayhi wa sallam, said: "Whoever catches one Rak‘ah from Jumu‘ah is only to add another one to it. Whoever catches less than one Rak‘ah is to pray four Rak‘ahs." And because he did not catch up with one Rak‘ah, thus it cannot be a valid Jumu‘ah." [End quote]

Allaah Knows best.