Tafsir of Yusuf 12:95

They said, (that is, those addressed), "By Allah, you are indeed in your old error."

(That is, you are in your long-standing deviation from the truth due to excess in your love for Joseph, your frequent mention of him, and your expectation of meeting him, with the condition being deeply rooted and persistent).

Ibn Jarir narrated from Mujahid that 'error' here carries the meaning of love. Muqatil said: It is misery and hardship. It has also been said: It is destruction and disappearance, derived from the expression, "The water was lost (dalla) in the milk," meaning it disappeared and perished within it. Ibn Abi Hatim narrated from Sa'id ibn Jubayr its interpretation as madness, which is something inappropriate; it seems it was for such an interpretation that Qatadah said, "They spoke a harsh word that people like them should not have said to someone like him, peace be upon him." Perhaps they only said this because they thought he had died.