The Messenger of Allah ﷺ used to pause between the verses of his recitation. He would say, "In the name of Allah, the Most Gracious, the Most Merciful" [Fatihah 1:1], then pause. Then he would say, "All praise is due to Allah, Lord of all the worlds" [Fatihah 1:2], then pause. Then he would say, "The Most Gracious, the Most Merciful" [Fatihah 1:3], then pause. Then he would say, "Master of the Day of Judgment" [Fatihah 1:4]. In this way he would break up his recitation, verse by verse.
كان رسول الله ﷺ يقطع قراءته يقول: {بسم الله الرحمن الرحيم} ثم يقف، ثم يقول: {الحمد لله رب العالمين} ثم يقف ثم يقول: {الرحمن الرحيم} ثم يقف، ثم يقول: {ملك يوم الدين} هكذا يقطعه قراءته آية آية.
Abu Dawud (4001) and Tirmidhi (2927) both narrated it through the route of Yahya bin Saeed Umawi, who said, Ibn Jurayj narrated to us, from Ibn Abu Mulayka, from Umm Salama, and he mentioned it. Tirmidhi said, "This is a hadith gharib, and Abu Ubayd holds this view and prefers it. This is how Yahya bin Saeed Umawi and others narrated from Ibn Jurayj, from Ibn Abu Mulayka, from Umm Salama, but its chain is not connected, because Layth bin Saad narrated this hadith from Ibn Abu Mulayka, from Yaala bin Mamlak, from Umm Salama, and Layth's hadith is more sahih. Layth's hadith does not contain the phrase 'and he used to recite "Malik of the Day of Judgment."'"This is how Tirmidhi criticized it as disconnected, but the correct view is that both routes are sahih, for it is possible that Ibn Abu Mulayka met Umm Salama. This is why Daraqutni (118), after citing the hadith, said, "Its chain is sahih and all its narrators are trustworthy." Hakim (2/231), after narrating it through the route of Yahya bin Saeed, said, "Sahih according to the criterion of the two sheikhs [Bukhari and Muslim]." Moreover, Ibn Jurayj is corroborated in the narration of Imam Ahmad (6/288), who said, Waki narrated to us, from Nafi bin Umar. And Abu Amir said, Nafi narrated to us, from Ibn Abu Mulayka, from one of the wives of the Prophet ﷺ. Abu Amir said, Nafi said, "I think she was Hafsa," that she was asked about the recitation of the Messenger of Allah ﷺ. She said, "You would not be able to do it." It was said to her, "Tell us about it." So she recited a recitation in which she paused deliberately between phrases. Abu Amir said, Nafi said, "Ibn Abu Mulayka related to us that she recited "Praise be to Allah, Lord of the worlds" [Fatihah 1:2], then paused, then "the Compassionate, the Merciful" [Fatihah 1:3], then paused, then "Master of the Day of Judgment" [Fatihah 1:4]."Ahmad's two teachers in this hadith are Waki, who is Ibn Jarrah, and Abu Amir, who is Abdul-Malik bin Amr Aqdi.As for the two recitations, "Malik of the Day of Judgment" and "Malik of the Day of Judgment" [with the shorter vowel], both are mutawatir.As for what Ibn Khuzayma (1/248) narrated from Muhammad bin Ishaq Sanani, who said, Khalid bin Khidash narrated to us, who said, Umar bin Harun narrated to us, from Ibn Jurayj, from Ibn Abu Mulayka, from Umm Salama, that the Prophet ﷺ recited in prayer, "In the name of Allah, the Compassionate, the Merciful" [Fatihah 1:1], counting it as one verse, and "Praise be to Allah, Lord of the worlds" [Fatihah 1:2] as two verses, and "and it is You we ask for help" [Fatihah 1:5], and he pressed together his five fingers, this narration is daif.Dhahabi said in Talkhis Mustadrak (1/232), "They agree that Umar bin Harun Balkhi is daif." Nasai said, "He is discarded (matruk)." Bayhaqi (2/44) also indicated his weakness, after citing it from the route of Ibn Khuzayma, saying, "Umar bin Harun narrated it, and he is not strong, from Ibn Jurayj, and he added to it."For more, see Minna Kubra (1/464).