The ruling on intending to fast a voluntary fast during the day

Question:
The questioner, Abu Muhammad, says: Shaykh, I want to follow the Messenger (peace and blessings be upon him), especially in the matter of fasting. The Messenger (peace and blessings be upon him) used to ask his family if they had anything to eat, and if not, he would say, “I am fasting.” If I told my family that I got up for the Fajr prayer and did not eat anything, and then asked them for food, and they said they had nothing, may I continue my fast?

Answer:
Yes, it is permissible to intend a voluntary fast during the day if one has not eaten anything after the dawn has appeared. In that case, he may make the intention during the day before the sun reaches its zenith. Yes.