All perfect praise be to Allah, The Lord of The Worlds, and may His peace and blessings be upon our Prophet Muhammad and upon all of his family.
Smearing one's self by the relics of the Prophet (PBUH) during his lifetime and after his death is permissible; whether this took place through kissing, touching, smearing and the like. And this applies on his wears and other personal belongings and tools.
It was confirmed that the righteous companions used to do so at the presence of the Prophet (PBUH) and he didn't disapprove it, since his body is full of blessings, besides there is no single disagreement among scholars in this regard. In addition to many narrations that were reported in this regard, and they read as follow:
First: Um Attiah (May Allah be pleased with her) narrated:" The Prophet entered upon us while we were washing his daughter and threw his waist-wrap to us and said (What means):"Shroud her in it." [Agreed upon]. An-Nawawi added:" The point behind shrouding her with Prophet's waist-wrap is to make her blessed."
Second: The narration of Abu Ayyub Ansari) who used to prepare food for Allah's Apostle (PBUH); and when it was brought (back) to him he asked (to locate) the part, where his fingers had touched (the food), and he followed his fingers on that part where his fingers (those of the Holy Prophet) had touched it." [Related by Moslim].
Third: Asma’ daughter of Abu Bakr (May Allah be pleased with them) said:" This was God’s messenger’s mantle which was with ‘A’isha, which I inherited when she died. The Prophet used to wear it, and we washed it for the sick and sought a cure by means of it. [Related by Moslim].
Fourth: Al-Imam Al-Bukhary established a chapter in his "Sahih", entitled with: "The armour of the Prophet (PBUH), his stick, sword, vessel, ring, and the like in which the manner of their division is unknown and been used by Caliphs such as: his hair, sandals and a cup out of what the righteous companions and others who used to seek the blessings from them right after the death of the Prophet (PBUH)."
In this respect, the narration of Issa Ibn Tahman, which says:" Anas brought out to us two worn out leather shoes without hair and with pieces of leather straps. Later on Thabit Al-Banani told me that Anas said that they were the shoes of the Prophet."
Further, Abu Burdah said:" Aisha brought out to us a patched wool Len garment, and she said: "(It chanced that) the soul of Allah's Messenger (PBUH) was taken away while he was wearing this." Asim narrated from Ibn Sereen that Anas Ibn Malik (May Allah be pleased with him) said: "When the cup of Allah's Messenger (PBUH) got broken, he fixed it with a silver wire at the crack. (The subnarrator, `Asim said, "I saw the cup and drank (water) in it.")
Fifth: Another chapter as well was established by Al-Bukhary in his "Sahih" and is entitled with:" Drinking from the bowl of the Prophet (PBUH) and his cups" in which, Abu Burda said: "Abdullah bin Salam met me and said to me, "Accompany me to my house so that I may make you drink from a bowl from which Allah's Messenger (PBUH) used to drink.
As well as, the last narration on this matter, the cup of Sahl Ibn Sa'ad from which the Prophet (PBUH) used to drink, then Umar b. 'Abd al-'Aziz asked him to give that (cup) as a gift to him and he did." And Allah Knows Best.
