"Messenger of Allah said [to me]: 'Do not say the Tathwib for any prayer except the Fajr prayer.'" [He said:] There is something on this topic from Abu Mahdhurah. Abu ʿEisa said: We do not know of the Hadith of Bilal except as a narration of Abu Isra'il Al-Mula'i. Abu Isra'il did not hear this Hadith from Al-Hakam bin ʿUtaibah. He said: He only reported it from Al-Hasan bin ʿUmarah, from Al-Hakam bin ʿUtaibah. Abu Isra'il's name is [Ismaʿil bin Abi Ishaq, and he is not strong according to the people of Hadith. The people of knowledge have differed over the interpretation of At-Tathwib. Some of them say that At-Tathwib is when one says "As-Salatu Khairummin An-Nawm, (prayer is better than sleep)" for the Adhan of Fajr. This is the saying of Ibn Al-Mubarak and Ahmad. Ishaq said something different about At-Tathwib, he said: "[The disliked Tathwib] is something that the people started after the Prophet; when the Mu'adh-dhin calls the Adhan and the people are slow in coming, so between the Adhan and the Iqamah he says: 'Qad Qamatis-Salat, Hayya ʿAlasalat, Hayya ʿAlalFalah. (Prayer is ready, come to prayer, come to success.)" [He said:] This Tathwib, which Ishaq mentioned, is the one that the people of knowledge dislike, which they innovated after the Prophet. But Ibn Al-Mubarak and Ahmad explained that At-Tathwib is when the Mu'adh-dhin says: "As-Salatu Khairum minan-Nawm, (prayer is better than sleep)" for the Adhan of Fajr. And this is the correct saying, and it is called At-Tathawwub as well, and this is the one chosen by the people of knowledge, and it is their opinion. It has been reported from ʿAbdullah bin ʿUmar that he would say: "As-Salatu Khairum-minan-Nawm, (prayer is better than sleep)" for Fajr. It has been reported from Mujahid that he said: "I entered a Masjid with ʿAbdullah bin ʿUmar in which the Adhan was called, and we wanted to pray in it. Then the Mu'adh-dhin said the Tathwib. So ʿAbdullah bin ʿUmar left the Masjid and said: 'Let us leave the place of this innovator' And he did not pray in it." [He said:] ʿAbdullah only disliked the Tathwib that the people invented later on.  

لِي رَسُولُ اللَّهِ ﷺ لاَ تُثَوِّبَنَّ فِي شَيْءٍ مِنَ الصَّلَوَاتِ إِلاَّ فِي صَلاَةِ الْفَجْرِ قَالَ وَفِي الْبَابِ عَنْ أَبِي مَحْذُورَةَ