Is it permissible to pray behind the row if the rows are full?

The questioner : I entered the mosque and there were full rows, so I prayed alone; no one joined me, I was by myself. Is my prayer permissible or not?

The Shaykh : Yes, there is a distinction.

The questioner : Yes, may Allah reward you.

The Shaykh : According to my view, it is permissible and it is not permissible.

The Shaykh : The audience : They laugh.

The questioner : Give us the permissible case and give us the case that is not permissible.

The Shaykh : It is permissible if you look in front of you in the last row, and the one before it, and the one before that, until you reach the imam, and you do not find a gap for you to fill. In this case, it is permissible for you to pray alone, and your prayer is valid. As for the first case, where you were lax, negligent, and did not look in front of you—may Allah be great—especially if you saw the imam raising his head from the bowing and you prayed alone, your prayer is invalid. This is because it is obligatory for you to join the row in front of you, at the very least. If you find an excuse that prevents you from joining this row, or the one before it, or the last one, if you find the excuse, the prayer is valid. If you do not find the excuse, the prayer is not valid.

The questioner : May Allah reward you.

The Shaykh : And may He bless you.

The questioner : He says this statement; Ibn Taymiyyah says this, and Ibn Taymiyyah has no evidence for it.

The Shaykh : Which statement?