Where can I find a good explanation for the hadith of Hasan and Husain رضي الله عنهما playing on Rasūl Allāh 's صلي الله عليه وسلم back during Śalāh? I'm actually looking for something that explains it as not being an evidence for children being disruptive in the masjid (as opposed to the opposite).
بِسْمِ اللهِ الرَّحْمنِ الرَّحِيْم
In the name of Allah, the Most Gracious, the Most Merciful
The hadith in question is as follows: “The Messenger of Allaah came out to us for one of the evening prayers (Maghrib or ‘Isha’), carrying Hasan or Husayn. The Messenger of Allaah came forward, put the child down and said Takbeer (“Allaahu Akbar”) to start the prayer. Then he prostrated during the prayer and his prostration lasted for a long time. My father said: I raised my head and saw the child on the back of the Messenger of Allaah, so I went back to my prostration. When the Messenger of Allaah finished praying, the people said to him: ‘Messenger of Allaah, during your prayer you prostrated and it took a long time, until we thought that something had happened, or that you were receiving Revelation.’ He said, ‘Nothing happened, but my son was riding on my back and I did not want to hurry him up until he had had enough.’”
There are some commentaries on the Sunan of An-Nasa’i which would explain this hadith in more detail. However, there is no need to disprove such an argument because this hadith does not indicate that the children were being disruptive or making any noise at all. Simply looking at the wording of the hadith, there is no indication at all that the boy was causing any disturbance, therefore the argument that those people are making not only has any basis but is contrary to the general principle that no one should disturb others during prayer, especially in the masjid.
Only Allah knows best
Written by Maulana Mustafa Umar
Checked and approved by Mufti Mohammed Tosir Miah
Darul Ifta Birmingham
 An-Nasa’i #1141