Shaykh Muqbil Bin Hadi Al-Wadi’i was asked:
Should a person use the siwaak during the day in Ramadan in specific times?
No, there isn’t a specific time [allotted to use the siwaak]. As for the [narration] which has been reported to that effect:
“When you fast, use the siwaak in the morning but do not use it in the afternoon.”
then it is a weak Hadith and it is reported by al-Daaraqutni.
That which is correct is that the Prophet [peace be upon him] said
“Were it not for the fact that I did not want to make things too hard for my ummah, I would have commanded them to use the siwaak at every time of prayer.”
[Tape “Rulings pertaining to fasting” by Shaykh Muqbil, rahimahullah]