Sending blessings upon the Prophet (peace and blessings be upon him) is prescribed in the first and last tashahhud

Q: From M. A. S. - Eritrea. Is the obligatory prayer or supplication valid if the Prophet (peace and blessings be upon him) is not mentioned in it? Some people have said that the prayer and supplication are not accepted unless they include sending blessings upon the Prophet (peace and blessings be upon him). Please inform us; may Allah reward you?

A: Praise be to Allah, and may blessings and peace be upon the Messenger of Allah. As for what follows:
Sending blessings upon the Prophet (peace and blessings be upon him) is prescribed in our obligatory and voluntary prayers, specifically in the tahiyyat at the end of the prayer, after one says: "I bear witness that there is no god but Allah, and that Muhammad is His slave and His Messenger." One then says: . There are other types established from the Prophet (peace and blessings be upon him); if one performs any one of them, it is sufficient, such as saying: .
Or saying: .
There are other types as well; if one performs any type of them that is authentic from the Prophet (peace and blessings be upon him), his prayer is valid and it is sufficient. Then, after that, he seeks refuge with Allah from four things: from the punishment of the Fire, from the punishment of the grave, from the trial of the Dajjal (the false messiah), and from the trial of life and death. He then supplicates with whatever good supplication he wishes before he says the closing salam.
This sending of blessings is also prescribed in the first tashahhud according to the correct view. Most scholars said that it is not prescribed except in the last tashahhud, but the correct view is that it is also prescribed in the first tashahhud, due to the generality of the hadiths reported regarding this. However, in the last tashahhud, it is a pillar or an obligatory duty that is necessary. As for the first tashahhud, it is recommended, because it is established from the Prophet (peace and blessings be upon him) what indicates leaving it out in the first tashahhud, which indicates that it is not obligatory in it.
The scholars have differed on whether it is a pillar, an obligatory duty, or a recommended practice in the last tashahhud, with the following opinions:
It was said: It is a pillar that is necessary, and the prayer is not valid without it. This is the well-known view of Imam Ahmad ibn Hanbal (may Allah have mercy on him) and a group of scholars.
It was said: It is obligatory; if one intentionally leaves it out, the prayer is invalid, but if he forgets it, the prayer is not invalid, but he performs the prostration for forgetfulness. This is the middle opinion.
Others said: It is a recommended practice; the prayer is not invalidated by leaving it out, whether intentionally or by forgetfulness, but it is a strongly recommended practice. This is because when the Messenger (peace and blessings be upon him) was asked how we should send blessings upon you, he said: etc. If it had been obligatory, he would have made it obligatory for them before they asked him and explained it to them along with the tashahhud.
In any case, what a Muslim should do is perform it and maintain it in the last tashahhud, because the Messenger (peace and blessings be upon him) commanded it, and the command implies obligation. Therefore, a believer should not leave it out in the last tashahhud, and the same applies to a believing woman. As for the first tashahhud, if he performs it, that is better and more excellent, and if he does not perform it, there is no blame on him. However, performing it is not a condition for acceptance, as there is no evidence for that.
We have mentioned the disagreement regarding its obligation in the last tashahhud.
As for supplication in the last tashahhud, it is recommended, but it is not a condition for acceptance. If one does not supplicate in the last tashahhud, his prayer is valid and there is no blame on him for that. However, it is recommended for him to supplicate in the last tashahhud after sending blessings upon the Prophet (peace and blessings be upon him) and after seeking refuge from the four things mentioned earlier, due to his saying (peace and blessings be upon him): . And his saying (peace and blessings be upon him) when he taught Ibn Mas'ud the tashahhud: . It is also established from him (peace and blessings be upon him) that he heard a man supplicating in his prayer without praising Allah or sending blessings upon the Prophet (peace and blessings be upon him), so he said: . Then he called him and said (peace and blessings be upon him): . It was narrated by Imam Ahmad, Abu Dawud, al-Tirmidhi, and al-Nasa'i, and al-Tirmidhi, Ibn Hibban, and al-Hakim graded it as authentic, and its chain is sound.
It is prescribed for the believer to strive for the causes of acceptance, such as eating lawful food and supplicating with a present heart that is fearful, hopeful, seeking pardon from his Lord, and far from sins. He should also seek the times of acceptance: at the end of the prayer before the salam, in prostration, between the adhan and the iqamah, in the last part of the night, and after the 'Asr prayer on Friday until the sun sets, while he is waiting for the Maghrib prayer, and when the preacher ascends the pulpit on Friday until the prayer is completed. And Allah knows best.