It is narrated from Hazrat Abu Bakrah (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) said: None of you should say, "I stood (in prayer) for the entire Ramadan," (because there is no way to avoid negligence or falling asleep; it is possible that one may sleep through a day).
Hadith Referenceمسند احمد / أول مسند البصريين / 20521
Hadith Gradingحکم دارالسلام:إسناده ضعيف، الحسن مدلس، وقد عنعن