Sayyiduna Abu al-Darda' (may Allah be pleased with him) relates that my beloved (peace and blessings be upon him) advised me of three things that I should not abandon as long as I live: "Fasting three days of every month, the Duha (forenoon) prayer, and not sleeping until I have prayed witr."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 4896