Is saying Taslim obligatory?

A: First: Reciting Taslim is obligatory according to the saying of the Prophet (peace be upon him): and its end is Taslim (final salutation). Related by the Five Compilers of Hadith except An-Nasa'iy (Ahmad, Abu Dawud, Al-Tirmidhy and Ibn Majah). Al-Tirmidhy said: This is the only most authentic and sound Hadith in this regard. Also according to a long Hadith narrated by `Aishah (may Allah be pleased with her) in which she said: He (the Prophet) used to finish the Salah with Taslim (salutation of peace ending the Prayer). Related by Muslim in his Sahih book. Second: Whoever offers Salah should recite Taslim twice, one to the right and one to the left side. This is what has been authentically reported about the deeds of the Prophet (peace be upon him) in Salah according to the Hadith narrated by the Five Compilers of Hadith (Imams Ahmad, Abu Dawud, Al-Tirmidhy, Al-Nasa`iy, and Ibn Majah) and classified as Sahih by Al-Tirmidhy on the authority of Ibn Mas`ud (may Allah be pleased with him) that he said: The Prophet (peace be upon him) used to give the salutation to his right and left sides saying: Peace be upon you, and mercy of Allah twice, until the whiteness of his cheek was seen. On the authority of `Amir ibn Sa`d from his father that he said: The Prophet (peace be upon him) used to offer Taslim (salutation on finishing prayer) to his right and left sides until the whiteness of his cheek was seen. Related by Ahmad, (Part No. 7; Page No. 69)  Muslim, Al-Nasa'y and Ibn Majah. These two Hadiths and other Hadiths to the same effect are proofs of those who say that Taslim should be made on both sides. Al-Shawkany said: This is the soundest opinion, for the Hadiths that are authentically reported about reciting Taslim to both sides are many. Some of these are Sahih (a Hadith that has been transmitted by people known for their uprightness and exactitude; free from eccentricity and blemish) and others are Hasan (a Hadith whose chain of narration contains a narrator with weak exactitude, but is free from eccentricity or blemish), and all of them confirm the additional phrase of "Wa Rahmatu Allah" i.e. (and mercy of Allah). Unlike the few Hadiths that suggest reciting Taslim to one side. These are Da`if (weak) Hadiths and can not be considered as good evidence. Supposing they are raised up to the level of good evidence, still they should not be acted upon as they are contradicted by many other authentic Hadiths supporting reciting Taslim to both sides. Third: The way in which a person should recite Taslim is to say: 'As-Salamu Alykom War Rahmatu Allah" i.e., (Peace and mercy of Allah be upon you) according to the Hadiths mentioned above Imam Muslim narrated in his Sahih Book on the authority of Jabir ibn Samurah (may Allah be pleased with him) that he said: When we observed prayer with the Prophet ( peace be upon him), we used to pronounce: Peace be upon you and Mercy of Allah, Peace be upon you and Mercy of Allah, and made gesture with the hand on both sides Abu Dawud narrated in his Sunan (Hadith compilations classified by jurisprudential themes) on the authority of Wa'il ibn Hujr (may Allah be pleased with him) that he said: I offered prayer along with the Prophet (peace be upon him). He would give the salutation to his right side (saying): Peace, mercy, and blessings of Allah be upon you; and to his left side (saying): Peace and mercy of Allah be upon you. Al-Hafiz ibn Hajar mentioned in his book Bulough Al-Maram that the Sanad (chain of narrators) of this Hadith is authentic and the Hadith means that the Prophet (peace be upon him) used to do this sometimes. The most common practice is just to say: 'As-Salamu Alykom Wa Rahmatu Allah' i.e. (Peace and mercy of Allah be upon you), to combine between the Hadiths reported in this matter. (Part No. 7; Page No. 70) May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.