Evidence for the validity of the prayer of an obligated person who prayed behind a voluntary-prayer leader?

The questioner : Peace, Khalid, that is fine.

The Shaykh : Yes, very well, what is the evidence for it?

The questioner : Several pieces of evidence. The first piece of evidence is the saying of the Prophet (peace and blessings be upon him) and the second piece of evidence is what is established in the Sahih from Mu'adh ibn Jabal that he used to the 'Isha' prayer, then he would go and pray the 'Isha' prayer as a voluntary prayer with his people, while they were praying it nearby,

The Shaykh : Yes.

The questioner : The third Thursday. Yes. Praise be to Allah.

The Shaykh : The third aspect, the third indication. Yes. Yes. No.

The questioner : The hadith of 'Amr ibn al-Salamah, where he led his people in prayer while he was six or seven years old, and we say that even if they said that perhaps the Prophet (peace and blessings be upon him) did not know, we say that

The Shaykh : No, no, no, wait, wait, what is this? The aspect of the indication.

The questioner : I have reached the Amir, I am walking.

The Shaykh : Yes, yes, the discussion is with you now.

The questioner : The most severe of the matters is that this is a boy, whereas for adults it is the minimum, as for the maximum.

The Shaykh : And the prayer in his case is voluntary.

The questioner : Yes.

The Shaykh : Very well, these are three.

The questioner : One of the forms of the prayer of fear, he prays with one of the two groups, so it becomes an obligatory prayer for him, then he needs the other group, and he prays with them, so it becomes a voluntary prayer for him, in his case it is voluntary, and he is in the case of an obligatory prayer,

The Shaykh : Perfect.