(Qa'idah Ihtiram Mal al-Muslim)

It's Meaning: What is intended by The Sanctity of The Property of a Muslim in this context is the prohibition of its unauthorised, transgressive or unlawful usage.
Al-Shaykh Murtadha al-Ansari, may God be pleased with him, has stated as regards this matter that the benefits and services are a form of liability in a void lease-contract (al-ijarah al-fasidah): Every act performed by an agent for someone else, in accordance to their request and the attainment of their objective, has to necessary be compensated for, in accordance with the two Precepts of "Sanctity" and "No Detriment" (al-ihtiram wa al-dharar).(1)

The Source: It is possible to demonstrate the Precept by the following:
I. Traditions: Traditions are found in various chapters in relation to the non-permissibility of utilising the property of a Muslim, except by his consent. It is from the unrestricted nature of these reports that the Precept is derived. These reports shall be cited in the context of other precepts, God willing. Here we shall suffice with mentioning one tradition that is explicit in its application regarding the Precept: The Prophet (s) stated: "the abuse of a believer is immoral…" to the extent that he (s) said, "the sanctity of his wealth is like the sanctity of his blood/life". (2)
This Authentic (al-Sahihah) report indicates that the property of a Muslim is sacred and the analogy between it and the blood/life of a Muslim directs us to the utmost importance of it, since blood/life is from among the most important issues in Jurisprudence.
Al-Muhaqqiq al-Gharawi also indicates to it by his statement: "the Precept of Sanctity is taken from the statement of the Prophet (s) and the sanctity of the property [of a Muslim/believer] is like the sanctity of the blood [of a Muslim/believer].(3)

(1)Al-Makasib: al-bay', p. 103
(2)Usul al-Kafi: vol. 2, p. 268 in the chapter of the Abuse of a believer, tradition 2

(3)Footnote of al-Makasib: vol. 1, p. 87

II. Judicial Concurrence (al-Tasalum): There is Concurrence of Judicial opinion amongst the scholars regarding the meaning of the Precept [of the sanctity of property of a Muslim], without disagreement.

III. The conduct of the Mutasharri'ah: (4) The Conduct of