Wearing a necklace on which it says “Ya Muhammad”
Question

                It has become popular among people to wear necklaces on which it says “Ya Muhammad”. What is the ruling on wearing it around one’s neck or hanging it in one’s car?.
Praise be to Allah.
    It is not permissible to write “Ya Muhammad” on the 
    necklace. 

    Firstly: because this wording is akin to du’aa’, and it is 
    well known that it is not permissible for anyone to call upon anyone other 
    than Allaah, because Allaah says (interpretation of the meaning):  

    “And the mosques are for Allaah (Alone), so invoke not 
    anyone along with Allaah”

    [al-Jinn 72:18] 

    “And who is more astray than one who calls  on (invokes) 
    besides Allaah, such as will not answer him till the Day of Resurrection, 
    and who are (even) unaware of their calls (invocations) to them?”

    [al-Ahqaaf 46:5]

    And the Prophet  (peace and blessings of Allaah be upon 
    him) said to Ibn ‘Abbaas (may Allaah be pleased with him): “If you ask, then 
    ask of Allaah, and if you seek help, then seek the help of Allaah.” Narrated 
    by al-Tirmidhi (2516); classed as saheeh by al-Albaani in Saheeh Sunan 
    al-Tirmidhi. 

    Secondly: Some of the ignorant wear these necklaces or hang 
    them in their cars in the belief that they bring some benefit and ward off 
     some harm, and they seek blessing from it, thereby falling into shirk, 
    because the Prophet  (peace and blessings of Allaah be upon him) told us 
    that wearing amulets is shirk. As narrated by Abu Dawood (3883) and classed 
    as saheeh by al-Albaani in Saheeh Abi Dawood. 

    It is well known that Islam came to block every route that 
    may lead to shirk. 

    Moreover the rights that the Prophet  (peace and 
    blessings of Allaah be upon him) has over us are many, and they cannot be 
    fulfilled merely by putting his name on necklaces, medallions and frames. 

    The rights of the Prophet  (peace and blessings of Allaah 
    be upon him) over us are that we should believe in him and in what he told 
    us, obey his commands, heed his prohibitions, submit to his rulings and 
    accept them, follow his Sunnah, send blessings upon him ( (peace and 
    blessings of Allaah be upon him)), defend him and refute those who criticize 
    him and disbelieve in him. May Allaah send blessings and peace upon him. And 
    Allaah knows best.