Hadith 1752
Sayyiduna Abu Hurairah (may Allah be pleased with him) said: The Messenger of Allah (peace and blessings be upon him) said: "Whoever does not fast a single day of Ramadan without a valid excuse or illness, then even if he fasts for his entire life, it will not make up for that day."
Hadith 1753
It is narrated from Sayyiduna Abu Hurairah (may Allah be pleased with him) that the Noble Prophet (peace and blessings be upon him) said: "Whoever, without a valid excuse for which Allah Almighty has granted permission (such as travel or illness), misses a single fast of Ramadan, then fasting for the whole lifetime will not make up for it."