He writes the name of Allaah on the workers’ caps to remind them of Allaah
Question

                Is it permissible that I write tasbeeh and adhkaar on the hats of those who work in industrial associations? I do this in order to remind them of Allah. But I was told that it belittles Allah’s name.
Praise be to Allah.
    The name of Allaah should not be written on these caps, so as 
    to protect His name from being disrespected and so as to free the wearer of 
    any inconvenience, because he may need to go to the toilet wearing this cap, 
    and it may be difficult for him to take if off every time he wants to do 
    that.  

    The way in which the name of Allaah may be disrespected in 
    this case is that the cap may be worn and taken off and placed on the floor 
    and so on, and it may be affected by dirt such as dust and sweat, or the 
    wearer may do something that Allaah has forbidden and disallowed, such as 
    smoking or backbiting about people, when he is wearing the name of Allaah 
    written on his head. 

    Shaykh Ibn ‘Uthaymeen (may Allaah have mercy on him) said 
    concerning the ruling on putting Qur’aanic verses on clothing: If the aim of 
    that is to exhort and remind people, we do not find that in the gatherings 
    where verses of Qur’aan are present (e.g. on the walls), we do not find that 
    they increase people’s piety or awareness of Allaah, rather in some of these 
    gatherings we see that evils are committed, where people smoke and backbite 
    about others and eat their flesh, and the book of Allaah is above their 
    heads, but they are gatherings in which Allaah is disobeyed. End quote from
    Liqaa’aat al-Baab il-Maftooh (2/54). 

    And Allaah knows best.