Hadith 52:2
Da'if (Darussalam)
It was narrated from Al-Hasan that he disliked to hire a man without telling him what his wages would be.
أَخْبَرَنَا مُحَمَّدٌ، قَالَ أَنْبَأَنَا حِبَّانُ، قَالَ أَنْبَأَنَا عَبْدُ اللَّهِ، عَنْ حَمَّادِ بْنِ سَلَمَةَ، عَنْ يُونُسَ، عَنِ الْحَسَنِ، أَنَّهُ كَرِهَ أَنْ يَسْتَأْجِرَ الرَّجُلَ، حَتَّى يُعْلِمَهُ أَجْرَهُ
Original Reference: Sunan an-Nasa'i 3858