Sayyiduna Abu Hurayrah (may Allah be pleased with him) narrates that the Messenger of Allah (peace and blessings be upon him) said: "Beware of continuous fasting (wisal)." They said: O Messenger of Allah! But you (peace and blessings be upon him) also practise wisal? He (peace and blessings be upon him) said: "In this I am not like you. When I spend the night, my Lord gives me food and drink. Do not burden yourselves with deeds that you do not have the strength for."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصيام / 8375