question #1 Sahih al-Bukhari 32, Book 2, Hadith 25 : What is considered a great injustice in the context of belief according to Islamic teachings?

When the following Verse was revealed: “It is those who believe and
confuse not their belief with wrong (worshipping others besides
Allah.)” (6:83), the companions of Allah’s Messenger (ﷺ) asked, “Who is
amongst us who had not done injustice (wrong)?” Allah revealed: “No
doubt, joining others in worship with Allah is a great injustice
(wrong) indeed.” (31.13)