“He is not strong.”

As for the other narrator—his uncle, ʿUbayd Allāh ibn ʿAbd al-Raḥmān ibn ʿAbd Allāh ibn Mawhib—al-Taqrīb describes him as “acceptable.”

From this you may see that the statement of al-Mundhirī, and after him al-Haythamī, that “Aḥmad transmitted it with a good chain,” is itself not well-founded. Nevertheless, taken together, the various routes render the ḥadīth ḥasan—indeed, ṣaḥīḥ.

It is, however, countered by the report of Abū Hurayrah (may Allah be pleased with him): “The Messenger of Allah ﷺ led us in one of the two late-afternoon prayers. He performed two rakʿahs, gave the salām, then rose to a beam that lay across the mosque, leaned against it as though displeased, placed his right hand upon his left, and interlaced his fingers …” —and so on.

Al-Bukhārī recorded this ḥadīth and entitled the chapter, “Interlacing the fingers in the mosque and elsewhere.”

The report indicates that interlacing the fingers inside the mosque is permissible. One could argue that the ruling is specific to the Prophet ﷺ, for the legal maxim holds that his explicit statement takes precedence over his action when the two appear to conflict. Alternatively— and this seems nearer to the truth—his action clarifies that the prohibition is not absolute but denotes mere reprehensibility. Allah knows best. See Nayl al-Aṭār for further discussion.