Among the Sunnah practices attached to the ẓuhr prayer, he states—under number 2 in the section on the merit of four rakʿahs before ẓuhr:

“If a person performs four before it or after it, the better course is to conclude with the taslīm after every two rakʿahs, although it is permissible to pray the four together with a single taslīm, for the Messenger of Allah ﷺ said: ‘The night-time and daytime prayers are to be offered two by two.’ Abū Dāwūd transmitted it with a sound chain.”

I say: One of the requisites of an authentic ḥadith is that its transmitter not differ from the other trustworthy reporters of the narration. That requisite is missing here, for the ḥadith appears in the two Ṣaḥīḥs and elsewhere through several chains from Ibn ʿUmar without the phrase “and daytime.” This extra wording is reported solely by ʿAlī ibn ʿAbd Allāh al-Azdī from Ibn ʿUmar, and none of the others who narrated it from him mention it. Al-Ḥāfiẓ said in Fatḥ al-Bārī, summarising the matter:

“Most of the ḥadith scholars have deemed this addition defective, because the reliable pupils of Ibn ʿUmar…”