It was narrated from Saeed bin Al-Musayyab that the Messenger of Allah said: "Whoever spends the nights of Ramadan in prayer (Qiyam) out of faith and in the hope of reward, he will be forgiven his previous sins"'.
The hadith also reminds us that we should not take our relationship with Allah lightly; rather, we should strive to make every effort possible during this special time so that we can reap its rewards both now and in the hereafter. We should remember that even though it may seem difficult at times, if we put forth sincere effort into worshipping Him then He will surely forgive us for any wrongdoings or mistakes made in the past.