All perfect praise be to Allah, The Lord of the Worlds, and may His peace and blessings be upon our Prophet Mohammad and upon all his family and companions.
Sending Prayers on the Prophet (PBUH) in the final Tashahhud, i.e. saying (Atahiya tu Lilah……and Allahouma Sali aala Mohammad…..), is a pillar of prayer, but in the first Tashahhud, it is an act of Sunnah. The evidence of this is the Hadith which An-Nawawi cited in his book [Al-Majmou` 3/461], and reads as follows: "When Allah's Messenger sat for the first two Rak'ah it was as if he was on hot stones." {At-Tirmizi}.
The phrase "Hot stones" indicates that he (PBUH) stood fast after pronouncing the first Tashahhud, and was brief in supplicating and on this basis, scholars have estimated the time span between the beginning of the Tashahhud and saying the prayers on the Prophet (PBUH). Although weak due to a break in the chain of narration between Abi Obaidah and his father, the above Hadith was also related by Abu Baker and Omar (May Allah be pleased with them). "
Sending prayers on the Prophet (PBUH) in the Tashahhud followed by Tasleem is an obligation, even if that prayer didn`t include a first Tashahhud, such as dawn(Fajir) prayer…..but the most preponderant opinion among scholars is that sending prayers on the Prophet (PBUH) in the first Tashahhud is an act of Sunnah…….However, the most correct opinion among the scholars is that sending prayers on the Prophet`s family in the first Tashahhud isn`t from Sunnah, as reflected from the Hadith mentioned earlier." {Al-Khateeb Ash-Shirbini, 1/380}.
In conclusion, in the first Tashahhud, one should say "atahiyat until Ashhadu an la Illaha illa Allah wa Ash-hadu an Mohammadn Rasolo Allah Allahouma Sali Ala Mohammad" then resume standing but in the final Tashhhud one should recite from" atahiyat until Fi al-alameen innka Hamidon Majeed." And Allah knows best.
