Source: Tafsir al-Ahlam al-Kabir (Ibn Sirin)
Sin in a dream indicates debt. Whoever sees himself committing a sin will fall into debt. Repentance from it is payment of the debt.
Source: Ta'tir al-Anam fi Ta'bir al-Manam (Al-Nabulsi)
Sin indicates worry and grief. Confessing it indicates repentance and high status.
Source: Al-Isharat fi Ilm al-Ibarat (Ibn Shahin)
Sin is interpreted as loss. Whoever sees himself committing a sin will lose in his trade.