It is narrated from Sayyidah Umm Salamah (may Allah be pleased with her) that the Messenger of Allah (peace and blessings be upon him) recited 'In the name of Allah, the Most Gracious, the Most Merciful' [Surah al-Fatihah: 1] in the prayer and counted it as one verse, 'All praise is for Allah, the Lord of the worlds' [Surah al-Fatihah: 2] as two verses, 'The Most Gracious, the Most Merciful' [Surah al-Fatihah: 3] as three verses, 'Master of the Day of Judgement' [Surah al-Fatihah: 4] as four verses, and likewise 'You alone we worship and You alone we ask for help' [Surah al-Fatihah: 5] as the fifth verse, counting them on his five fingers.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2385