Is it permissible to take revenge on someone who tried to assault one in the past, or is it better to forgive him?

Allah Almighty says: {But whoever pardons and makes reconciliation - his reward is due from Allah.} (Surat Ash-Shura, 42:40). However, admonish him and remind him of Allah if you are able. If he has repented, then conceal his secret, for the Prophet, peace and blessings be upon him, said: "Whoever conceals a Muslim, Allah will conceal him in this world and the Hereafter." If he is transgressing against others, and you are able to prevent his evil by informing the authorities, then do so, for the Prophet, peace and blessings be upon him, said: "Whoever among you sees an evil, let him change it with his hand; if he is not able, then with his tongue; if he is not able, then with his heart — and that is the weakest of faith."