It is narrated from Sayyiduna Ibn Mas'ud (may Allah be pleased with him) that once I submitted in the presence of the Messenger of Allah: O Messenger of Allah (peace and blessings be upon him)! What is the greatest injustice? The Prophet (peace and blessings be upon him) said: "That one span of land which a person takes from his brother by diminishing his right, on the Day of Resurrection, every single pebble of it will be made into a collar and placed around his neck, and the knowledge of the depth of the earth is only with the One who created the earth."