أَخْبَرَنَا مُحَمَّدُ بْنُ حَاتِمٍ، قَالَ أَنْبَأَنَا حِبَّانُ، قَالَ أَنْبَأَنَا عَبْدُ اللَّهِ، عَنْ شُعْبَةَ، عَنْ حَمَّادٍ، عَنْ إِبْرَاهِيمَ، عَنْ أَبِي سَعِيدٍ، قَالَ إِذَا اسْتَأْجَرْتَ أَجِيرًا فَأَعْلِمْهُ أَجْرَهُ‏.‏‏

It was narrated from Hammad -Ibn Abi Sulaiman- that he was asked about a man who hired a worker in return for food and he said

"No, not until he tells him (what his wages will be)."