al-Nisyān is interpreted in two ways:
1. al-Nisy is used in the sense of 'to abandon'; as in the following verses:
And We had already taken a covenant [obligation] from Adam before, but he forgot; {that is, he abandoned the covenant/obligation}. (Tā-Hā 20:115)
So taste [punishment] for what you forgot [abandoned] the meeting of this Day of yours. Indeed, We [too] will forget you [abandon you]. {That is, you abandoned iman (faith) in the meeting of this Day; and We abandoned you to punishment.} (al-Sajda 32:14)
And do not forget [abandon] graciousness between you! {That is, do not abandon graciousness among yourselves!} (al-Baqara 2:237)
Whatever verse (āya) We abrogate or cause to be forgotten [leave as is]... {That is, if We do not abrogate it but abandon it / leave it as it is} (al-Baqara 2:106)
2. al-Nisy is also used in the sense of 'that which is not forgotten / does not leave the mind and is uninterrupted (knowledge)'; as in the following verses:
We will make you recite, [O Muhammad], and you will not forget, {that is, We will preserve it so you will not forget it; it will not leave your mind}. (al-Aʿlā 87:6)
Indeed, I forgot the fish, {that is, the fish left my mind / slipped from my memory}. None made me forget it except Satan. (al-Kahf 18:63)
[Moses said to al-Khiḍr:] "Do not blame me for what I forgot {that is, for what left my mind / slipped from my memory}." (al-Kahf 18:73)