The intention to fast Ramadan
As salaamu alaikum wa rahmatullahi wa barakaatuh
Should the intention to fast Ramadaan be made at night or during the day? and if someone tells you at the time of duha (forenoon) that today it is Ramadan, should you make it up or not?
It is essential to make the intention to fast the month of Ramadan at night, before Fajr. It is not sufficient to start fasting it that day without the intention. Whoever finds out at the time of Duha that today it is Ramadan and makes the intention of fasting has to refrain from eating until sunset, and he also has to make up that day, because it was narrated by Ibn ‘Umar from Hafsah (Radiyallaahu ‘anhaa) that the Prophet (Sallallaahu’ alaihi wa sallem) said: “Whoever does not have the intention of fasting before Fajr, there is no fast for him.” [Authenticated by Al-Albani]
«من لم يجمع الصيام قبل الفجر فلا صيام له»
This is with regard to obligatory fasts. With regard to naafil fasts it is permissible to make the intention to fast on the day, if you have not eaten or drunk or had intercourse after Fajr, because it was proven in the hadeeth of ‘Aa’ishah (Radiyallaahu ‘anhaa) that the Prophet (Sallallaahu’ alaihi wa sallem) entered upon her one day at duha time and said, “Do you have anything (any food)?” She said, “No.” He said, “Then I am fasting.” [Narrated by Muslim in his Saheeh]
«قال لي رسول الله صلى الله عليه وسلم ، ذات يوم "يا عائشة! هل عندكم شيء ؟" قالت فقلت: يا رسول الله! ما عندنا شيء. قال "فإني صائم"...»
And Allaah is the Source of strength. May Allaah send blessings and peace upon our Prophet Muhammad and his family and companions.
Standing Committee for Research and Issuing Fatwas. 10 / 244