Sayyiduna Abu Hurayrah (may Allah be pleased with him) said that the Messenger of Allah (peace and blessings be upon him) said: "Whoever leaves one fast of Ramadan without an excuse for which Allah Almighty has granted him a concession, he cannot make it up even if he fasts the whole year."
Imam al-Tirmidhi (may Allah have mercy on him) said: I asked Imam al-Bukhari (may Allah have mercy on him) about this, and he said: Abu al-Mutawwis's name is Yazid bin al-Mutawwis; he is alone in narrating this hadith, and I do not know whether his father heard from Sayyiduna Abu Hurayrah (may Allah be pleased with him) or not.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصيام / 8065