A man once came to Ibn Mas‘ud, radiya’Llahu anh, and asked him: I have repeatedly committed a major sin – can there be any repentance for me? Ibn Mas‘ud turned away, and the man saw that his eyes had filled with tears. He said: ‘Paradise has eight gates, and each one of them is sometimes open and sometimes shut. With the exception of the Gate of Repentance, which is held open eternally by an angel who never leaves that place. So do not despair!’

Source: When the Generous appears with the Name Avenger by Shaykh Abdal-Hakim Murad