The siwak is a stick cut from the arak tree. It is used to clean the mouth and teeth, to perfume the mouth and to remove bad smells. It is one of the most emphatically confirmed Sunnahs of the Prophet (blessings and peace of Allah be upon him), as he often cleaned his teeth with a siwak and enjoined others to do likewise. It is more important to use it at some times than others, such as what is mentioned in this hadith, which speaks of offering voluntary prayers at night (qiyam al-layl). Hudhayfah ibn al-Yaman (may Allah be pleased with him) narrated that when the Prophet (blessings and peace of Allah be upon him) wanted to get up to pray qiyam al-layl and tahajjud, he would clean his mouth with the siwak, meaning that he would pass it over his teeth and rub them with it. He did that to take away any bad smell, so that he could recite Qur’an and offer du‘a’ in his prayer. This hadith highlights the virtue and importance of the siwak..