Does entering the mosque or praying without purity require expiation?

If what is meant by 'hadath' (ritual impurity) is the major impurity, then one who is in a state of major impurity (junub) is not permitted to remain in the mosque, but is allowed to pass through it, based on the Almighty's saying: "Nor as those who are impure, except when passing through, until you have bathed" (Qur'an 4:43), and due to the prohibition by the Prophet, peace and blessings be upon him, against it. As for one who has a minor impurity, it is permissible for him to enter the mosque and remain therein. However, prayer is not permissible for one who has a major or minor impurity. And whoever prays without purification, his prayer is invalid, and he must repeat it along with repentance and seeking forgiveness.