Is it permissible for the one entrusted with a sum of money to dispose of it, such as by lending it to another person?

It is obligatory for the trustee to safeguard the trust and not dispose of it except with the owner's permission; otherwise, he would be sinful and liable for its guarantee due to his transgression. Allah has magnified the importance of trusts and equated betrayal of them with betraying Allah and His Messenger, saying: "O you who have believed, do not betray Allah and the Messenger or betray your trusts while you know [the consequence]." And the Prophet, peace and blessings be upon him, said: "Render back the trust to the one who entrusted you, and do not betray the one who betrays you."