Akwai ƙunshiyar hayar aiki ko ɗaukar aiki wadda ta shafi amfanin aiki da amfanin mutum, kuma ita ce wadda ta shafi ma'aikaci. Ma'aikaci shi ne wanda ya ɗauki kansa haya. Shari'a ta halatta a yi hayar mutum saboda wani amfani da ke fitowa daga gare shi kamar hidima da makamancinta, ko amfanin da ke fitowa daga aikinsa kamar zane, rini, injiniya da makamancinsu. Domin a kulla ƙunshiyar hayar, cancantar ɓangarorin biyu sharaɗi ne na kulla ta, ta yadda kowannen su ya zama mai hankali kuma mai iya bambancewa. Ba a kulla hayar mahaukaci ba, haka nan ba a kulla hayar yaro marar balaga ba. Idan aka kulla hayar, yardar ɓangarorin biyu sharaɗi ne na ingancinta, kuma abin da aka kulla a kansa, wato amfanin, ya zama sananne ta hanyar da ke hana jayayya. Wannan sanin hidimar, dangane da ma'aikaci, wani lokaci ana yinsa ta hanyar bayyana lokaci, wani lokaci ta hanyar iyakance amfani, wani lokaci kuma ta hanyar kwatanta aikin da ake buƙata cikakken bayani, da kuma ƙayyade abin da ma'aikaci zai yi ko ƙayyade yadda zai yi aikin. Saboda haka, hayar wanda aka tilasta ba ta inganta ba, haka nan hayar amfani wanda ba a san shi ba ba ta inganta ba.

The contract of hiring or employment which came upon the benefit of work and the benefit of the person is the one which relates to the employee. The employee is one who hires himself. The Shar’a has permitted the hiring of the human being for a benefit resulting from him like service and the like or the benefit resulting from his work like painting, dyeing, engineering and the like. In order to contract the hiring, the fitness of the two contractors is a condition for its contracting such that each of the two should be sane and possessing discretion. The hiring of the insane is not contracted, nor the hiring of an immature child. If the hiring contracts, the consent of the two contractors is a condition of its validity, and that which is contracted upon— which is the benefit—be known in a way that prevents dispute. This knowledge of the service, in relation to the employee, at times is by explaining the period, at times by limiting the benefit or describing the required work in a detailed description and specifying what the employee will do or specifying how he will work. Accordingly, hiring the compelled person is not valid nor is the hiring of an unknown benefit valid.