The meaning is that they sent him to Yusuf. He came to him and said, 'O Yusuf, O truthful one, O eloquent one in truth.' He said this because he had experienced his conditions and recognized his truthfulness in interpreting dreams, both his own and that of his companion, as it came to pass as he interpreted. Therefore, he spoke to him with careful words, saying, 'Perhaps I may return to the people so that they may know.' This is because he is not certain of returning, for perhaps he may be cut off before that, and he is not sure if they know, so perhaps they do not know. Or the meaning of 'perhaps they may know' is that they may know your virtue and your status in knowledge, so they may seek you out and rescue you from your ordeal.