Yaum at Taghaabun
The Day that He assembles you (all) for a day of Assembly― that will be a day of mutual loss and gain (among you). (64:09)
Taghaabun: Day of the Mutual loss and gain.
The root of this word gives the meaning of a deficiency in someone’s intellect and also to fool/dupe someone because of their lack of intelligence. Another form of this word means to suffer loss in a financial transaction because the other person caused you loss secretly; they are gaining while you are losing. This word is also used for ghaflah/heedlessness and being deprived of one’s right.; it means a loss that a person suffers because of his lack of intellect and ghaflah.
Taghaabun is on the structure of tafaa’ul, meaning it is mutual. It is the day when people will take eachother’s haqq, their shares, the credit of another person’s efforts: this is taghaabun; one person suffers while another person gains, it is the Day that people will cause loss and failure to eachother.
Ibn Abbas said, “It is one of the names of the Day of Judgment, and that is because the people of Paradise will have gained over the people of the Fire.” Muqatil bin Hayyan said, “There is no mutual loss and gain greater than these entering Paradise and those being taken to the Fire.”