He prayed One Rak'ah Alone behind the Row, then when the Imam made the Taslim, He prayed a Fifth (Rak'ah)

Question :

If I start to pray just before the bowing, should I begin by reciting Surah Al-Fatihah, or the opening supplication... and if the Imam bows before I have finished Al-Fatihah, what should I do?

Answer:

The recitation of the opening supplication is a Sunnah and the recitation of Surah Al-Fatihah is obligatory, according to the most authentic of the sayings of the scholars.

So if you are afraid that you will not be able to recite Al- Fatihah, then start to recite it, and if the Imam bows before you have completed it, then bow with him (i.e. after him) and the rest of it will not be required of you, according to the Hadith of the Prophet

"The Imam is there to be followed, so do not conflict with him; if he says: "Allahu Akbar", then you say: "Allahu Akbar"; and if he bows, then you bow...

Question :

A man prayed alone (i.e. behind the last row), then in the second Rak'ah, another person began to pray with him... after the Imam made the Taslim, he prayed a fifth Rak'ah, because he considered that the first Rak'ah was not accepted, because he prayed it alone, behind the row. Was his prayer correct ... and what should a person who finds himself in this situation do?

Answer:

It has been authentically reported from the Prophet that he said:
"There is no prayer for one who prays alone behind the row.

And it has also been authentically reported from him that he saw a man praying behind the row, and he ordered him to repeat the prayer.

However, a person who bows behind the row, then enters the row before the prostration is credited with the Rak'ah, based upon the narration of Al-Bukhari in his Sahih in which it is stated that Abu Bakrah Ath-Thaqafi, may Allah be pleased with him, came to the mosque to find the Prophet bowing, so he bowed behind the row, then entered the row. And the Prophet said to him:

"May Allah increase you in endeavor, but do not repeat it.

- and he did not order him to make up for it, which proves that it was accepted,and that such an act is exempt from the words of the Prophet:

"There is no prayer for one who prays alone behind the row.» And Allah is the Granter of success.