Assalaamu alaikum, dear shaikh some websites say that when you use siwak keep your little finger at the end lowest back part of it. Is this true? 2 - They say when you intend to discard siwak then bury it somewhere rather to throw in the dustbin as it was a source of cleanliness and a honorable sunnah. Is it also true? Jazaak ALLAHU Khair.
All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
The jurists said that it is recommended to place the little finger and thumb under the Siwaak and the rest of the fingers over it.
The Hanafi scholar Ibn Nujaym said: "The Sunnah is to hold the Siwaak in the right hand with the little finger under the Siwaak, the ring, middle and index fingers over it and the thumb under its top (the bristle end) as Ibn Mas‘ood reported." [Al-Bahr Ar-Raa’iq]
The Maaliki book Haashiyat As-Saawi ‘ala Ash-Sharh As-Sagheer reads: "His statement 'with his right hand' means that one should hold the Siwaak in the right hand with the little finger and thumb under it and the three other fingers over it."
The Shaafi‘i book I‘aanat At-Taalibeen reads: "It is an act of Sunnah to hold the Siwaak with the right hand and to place the little finger under it, the ring, middle and index fingers over it, and the thumb under its tip.”
Al-Mawsoo‘ah Al-Fiqhiyyah Al-Kuwaytiyyah (Kuwaiti Encyclopedia of Jurisprudence) reads: "It is recommended to hold the Siwaak in the right hand because the Prophet, sallallaahu ‘alayhi wa sallam, was reported to have done so as narrated on the authority of ‘Aa’ishah : 'The Prophet, sallallaahu ‘alayhi wa sallam, liked to begin with the right whenever he could, when purifying himself and when putting on his sandals and combing his hair, and in all his affairs." [Al-Bukhari and Muslim]
Another version of the Hadeeth reads, "… and when using his Siwaak." He, sallallaahu ‘alayhi wa sallam, would place the little finger under the Siwaak and the other fingers over it, as Ibn Mas‘ood described." [End of quote]
As for what you said about the need to bury the Siwaak rather than throw it in the dustbin, we have not found any scholar who stated that this is obligatory or even recommended; the presumption concerning this is that it is permissible.
Allaah Knows best.
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