Is there a sound supplication narrated from the Messenger of Allah, may Allah bless him and grant him peace, when using the siwak? And what is the legal ruling on saying: "O Allah, purify my heart and cleanse my sins" when using the siwak? And is it legislated to say the recommended supplication at the beginning of using the siwak: "O Allah, whiten my teeth with it, strengthen my gums with it, and bless me, O Most Merciful of those who show mercy," based on the statement of Imam An-Nawawi?

There is no authentic evidence for a specific remembrance (dhikr) to be recited when using the siwak (toothbrush). However, some scholars have deemed it commendable to recite a dhikr that aligns with the purpose of the siwak. Al-Ruyani mentioned that some companions of Al-Shafi'i considered it desirable to say: "O Allah, whiten my teeth with it, strengthen my gums with it, firm my uvula with it, and bless me in it, O Most Merciful of the merciful." They considered this supplication good, even if it had no origin (in the Sunnah).