﴿ وَقَالَ لِلَّذِى ظَنَّ أَنَّهُۥ نَاجٍۢ مِّنْهُمَا ٱذْكُرْنِى عِندَ رَبِّكَ فَأَنسَىٰهُ ٱلشَّيْطَٰنُ ذِكْرَ رَبِّهِۦ فَلَبِثَ فِى ٱلسِّجْنِ بِضْعَ سِنِينَ ﴾

“And [thereupon Joseph] said unto the one of the two whom he considered saved: "Mention me unto thy lord [when thou art free]!" But Satan caused him to forget to mention [Joseph] to his lord, and so he remained in prison a few [more] years.”

After that, to the person about whom Sayyidna Yusuf (علیہ السلام) had gathered from the interpretation of his dream that he would be released, he said: When you are released from the prison, mention me before your master as the innocent person who is still languishing in the prison. But, once released, this person forgot about this message of Sayyidna Yusuf (علیہ السلام) ، as a result of which, his freedom was further delayed and he had to stay in prison for a few more years. The word used in the Qur’ an is: بِضْعَ سِنِينَ (bid'a sinin: a few years). This word holds good for a figure between three to nine. Some commentators have said that he had to live in the prison for a period of seven more years.