What is the linguistic derivation of the term 'Ijarah' (lease)?

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The term 'Ijarah' is derived from 'Ajr' (wages/rent), which signifies compensation. Allah states this derivation, saying: {If you had wished, you could have taken against it a payment} (Quran 18:77). The reward ('Thawab') given by Allah to the servant for obedience or patience during affliction is also termed 'Ajr' for this reason.