Is it necessary to ask for forgiveness if the person we have backbitten has not heard of it?

Can you explain these hadiths? Is it necessary to ask for forgiveness if the person we have backbitten has not heard of it?
If the person who was backbitten heard about it, the backbiter cannot be forgiven only by repentance. It is also necessary to ask for forgiveness from him. A hadith regarding the issue is as follows:
“Unless the person who was backbitten forgives the person who backbit, the backbiter will not be forgiven.” [Daylami]
If the person who was backbitten does not know about it, the backbiter will be forgiven by repenting and praying for him. He/she should make a dua as follows: “O Allah! Forgive me and the person whom I backbit!”
Two hadiths regarding the issue are as follows:
“The atonement of backbiting is praying for the forgiveness of the person who was backbitten.” [Ibn al-Lal]
“If the backbiter asks for forgiveness from Allah for the person whom he backbit, it will be atonement for the sin of backbiting.” [Khatib]

Dear Brother / Sister,

Backbiting is haram.

If the backbitten person heard about it and became aware of it, it is not enough for the backbiter to repent only and make dua for the person whom he backbit. He needs to ask for forgiveness from the person whom he backbit unless a bigger problem is certain to occur.

Backbiting is oppression. According to the hadiths, as a rule, the rights will be taken away from the oppressor and given to oppressed person in the hereafter unless the oppressor prevails the oppressed person on to forgive him in the world.

If the person who was backbitten is not aware of it, according to the most of the scholars, it is not necessary to inform him because there may be inconveniences, deterioration in relations between believers and committing other sins in general. The backbiter needs to make dua for the person whom he backbit, talk about his high ethics and good deeds in his absence, and help him in his work if possible.

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