This excerpt is taken from Sheikh Abu Hamza Abdul Khaliq Siddiqi's book Sahi Fazail-e-Amaal.
عن عبد الله بن عمرو بن العاص رضي الله عنهما قال: قال رسول الله صلى الله عليه وسلم: صوم ثلاثة من كل شهر صوم الدهر كله .
It is narrated from Sayyiduna Abdullah bin Amr bin Al-As, may Allah be pleased with them, that the Messenger of Allah, peace and blessings be upon him, said: "Fasting three days every month is equivalent to fasting continuously."
Reference: Sahih Bukhari, Book of Fasting, Chapter: The Fast of Dawood (peace be upon him), Number: 1979.
