Raising the Hands in Prayer
Question

This is regarding the Sahih Mutawatir Hadith of raising of the hands before and after the bowing in the Salat. This has been authentically reported in Sahih Al-Bukhari, Sahih Muslim, and Sunan Abu Dawud.
My question is, why do the Hanafis not accept this Hadith? What's their reasoning for not acting upon this sahih Hadith? 
A related question is, was this Hadith not available to Abu Hanifah (may Allah have mercy on him) at his time? What could be the reasons for this?
Praise be to Allah.Reported Hadith about raising hands in prayer
The Hadith to which the questioner refers was narrated by Al-Bukhari (735) and Muslim (390) from `Abdullah ibn `Umar (may Allah be pleased with him), who said that the Messenger of Allah (peace and blessings of Allah be upon him) used to raise his hands to shoulder level when he started to pray, when he said “Allahu akbar” before bowing in Ruku`, and when he raised his head from Ruku`. 
The majority of scholars followed this Hadith and said that it is recommended for the worshipper to raise his hands at the points mentioned in the Hadith . 
Imam Al-Bukhari (may Allah have mercy on him) wrote a separate book on this issue which he called Juz’ fi Raf` Al-Yadayn (Section on Raising the Hands), in which he proved that the hands should be raised at these two points on the prayer, and he strongly denounced those who go against that. He narrated that Al-Hasan (may Allah have mercy on him) said: “The Companions of the Messenger of Allah (peace and blessings of Allah be upon him) used to raise their hands during prayer when they bowed and when they stood up (from bowing).” Al-Bukhari said, “Al-Hasan did not exclude any of the Companions from that, and it was not proven that any one among the Sahabah did not raise his hands.” (See Al-Majmu` by An-Nawawi, 3/399-406)
Hadiths about not raising hands in prayer
We do not know whether the Hadiths about raising the hands reached Abu Hanifah (may Allah have mercy on him) or not, but they did reach his followers. But they did not follow them because they had other Hadiths and reports which said that the hands should not be raised except when saying “Allahu akbar” at the beginning of the prayer. 
These Hadiths include the following:  
The Hadith narrated by Abu Dawud (749) from Al-Bara’ ibn `Azib (may Allah be pleased with him), which says that the Messenger of Allah (peace and blessings of Allah be upon him) used to raise his hands almost to his ears when he started to pray, then he did not repeat (this action).
The Hadith narrated by Abu Dawud (748) from `Abdullah ibn Mas`ud (may Allah be pleased with him) who said: “Shall I not lead you in prayer as the Messenger of Allah (peace and blessings of Allah be upon him) did?” Then he prayed and he only raised his hands once. (See Nasb Ar-Rayah by Az-Zayla`i, 1/393-407) 
But these Hadiths were classed as inauthentic by the Imams of Hadith. 
The Hadith of Al-Bara’ was classed as inauthentic by Sufyan ibn `Uyaynah, Ash-Shafi`i, Al-Humaydi the shaykh of Al-Bukhari, Ahmad ibn Hanbal, Yahya ibn Ma`in, Ad-Darimi, Al-Bukhari, and others. 
The Hadith of Ibn Mas`ud was classed as inauthentic by `Abdullah ibn Al-Mubarak, Ahmad ibn Hanbal, Al-Bukhari, Al-Bayhaqi, Ad-Daraqutni and others. Similarly, the reports which were narrated from some of the Companions about not raising the hands are all inauthentic. We have quoted above the words of Al-Bukhari (may Allah have mercy on him): “…it was not proven that any one among the Companions did not raise his hands.” (See Talkhis Al-Habir by Al-Hafidh ibn Hajar, 1/221-223) 
Ruling on raising hands in prayer
Once it is proven that these Hadiths and reports which say that the hands should not be raised are inauthentic, then the Hadiths which say that the hands should be raised remain strong with no opposing reports. 
Hence the believer should not fail to raise his hands at the points in prayer described in the Sunnah. He should strive to make his prayer like the prayer of the Prophet (peace and blessings of Allah be upon him) who said, “Pray as you have seen me praying.” (Narrated by Al-Bukhari, 631)
Hence `Ali ibn Al-Madini (may Allah have mercy on him), the shaykh of Al-Bukhari, said: “It is the duty of the Muslims to raise their hands when they bow in Ruku` and when they stand up from Ruku`.” Al-Bukhari said: “`Ali was the most knowledgeable of the people of his time.” 
Once the Sunnah has been explained clearly, no one has the right to ignore it, following whoever among the scholars said that.  Imam Ash-Shafi` (may Allah have mercy on him) said: “The scholars are agreed that if the Sunnah of the Prophet (peace and blessings of Allah be upon him) becomes clear to a person, it is not permissible for him to ignore it in favour of the opinion of anyone.” (Madarij As-Salikin, 2/335) 
“If a man is following Abu Hanifah or Malik or Ash-Shafi`i or Ahmad, and he sees that the view of another Madhhab concerning a given matter is stronger, and he follows that, then he has done well, and that does not detract from his religious commitment or good character. There is no scholarly dispute on this point. Rather this is more in accordance with the truth and is more beloved by Allah and His Messenger.” (Said by Shaykh Al-Islam – may Allah have mercy on him – in Al-Fatawa, 22/247)
The scholars who said that the hands should not be raised based on their own Ijtihad are to be excused, for they will be rewarded for their Ijtihad and their seeking the truth, as the Prophet (peace and blessings of Allah be upon him) said: “If a judge passes judgement based on his own Ijtihad and he is correct, he will have two rewards; if he passes judgement based on his own Ijtihad and he makes a mistake, he will have one reward.” (Narrated by Al-Bukhari, 7352; Muslim, 1716) (See Raf` Al-Malam `an Al-A’immah Al-A`lam by Shaykh Al-Islam Ibn Taymiyah)
Note: 
There is a fourth place where it is recommended to raise the hands during prayer; that is when standing up after the first Tashahhud for the third Rak`ah.  
May Allah help us all to know the truth and follow it. 
And Allah knows best.  May Allah send blessings and peace upon our Prophet Muhammad.
And Allah knows best.