It is narrated from Sayyiduna Sa'd bin Abi Waqqas (may Allah be pleased with him) regarding the verse "Those who are heedless of their prayer" [Surah al-Ma'un: 5], "those who are lax in their prayers": In the recitation of Abdullah (may Allah be pleased with him), 'lahun' (distracted) is in place of 'sahun' (heedless). He said: 'Sahun' and 'lahun' mean forgetting the prayer and not paying attention to its time.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 3161