All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
Lying is to give information about something contrarily to the truth, and saying that Yousuf (Joseph) sighed and said ‘Allaah is enough for me’ is in our view saying without knowledge if it is not based on a Sharee’ah text, but we cannot authoritatively say that it is a lie as we do not know whether or not he said that.
However, who claimed that he [Yousuf] said that without relying on a Sharee’ah text about this, he has said what he had no knowledge of, and Allaah forbade us from doing so; Allaah Says (what means): {And do not pursue that of which you have no knowledge. Indeed, the hearing, the sight and the heart about all those [one] will be questioned.}[Quran 17:36]
Moreover, we have not come across this statement that is attributed to Yousuf in the reference books we have at hand; so Allaah Knows best what he said.
In case it is found in the books of the Children of Israel that he said this, then it is permissible to relate this as the Prophet said: “You may relate from the children of Isreal without objection.” [Al-Bukhari and Abu Daawood]
Allaah Knows best.