"When you hire a worker, tell him what his wages will be."  

إِذَا اسْتَأْجَرْتَ أَجِيرًا فَأَعْلِمْهُ أَجْرَهُ  

It was narrated from Al-Hasan that he disliked to hire a man without telling him what his wages would be.  

أَنْ يَسْتَأْجِرَ الرَّجُلَ حَتَّى يُعْلِمَهُ أَجْرَهُ  

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

لاَ حَتَّى تُعْلِمَهُ  

"I will lease (something) from you until I reach Makkah for such and such a payment, and if I travel for a month or such and such -something that he named- I will give you such and such in addition." They did not see anything wrong with that, but they did not like it if he said: "If I travel for more than a month I will deduct such and such from your lease."  

لِرَجُلٍ أَسْتَكْرِي مِنْكَ إِلَى مَكَّةَ بِكَذَا وَكَذَا فَإِنْ سِرْتُ شَهْرًا أَوْ كَذَا وَكَذَا شَيْئًا سَمَّاهُ فَلَكَ زِيَادَةُ كَذَا وَكَذَا فَلَمْ يَرَيَا بِهِ بَأْسًا وَكَرِهَا أَنْ يَقُولَ أَسْتَكْرِي مِنْكَ بِكَذَا وَكَذَا فَإِنْ سِرْتُ أَكْثَرَ مِنْ شَهْرٍ نَقَصْتُ مِنْ كِرَائِكَ كَذَا وَكَذَا  

"I said to 'Ata': 'What if I hire a slave for a year in return for his food, and for another year, in return for such and such?' He said: 'There is nothing wrong with that, and you may stipulate your conditions of hiring even for a few days.' 'How about if I make a deal to hire him when part of the year has passed?' He said: 'Do not hold me to account for what has passed.'"  

قُلْتُ لِعَطَاءٍ عَبْدٌ أُؤَاجِرُهُ سَنَةً بِطَعَامِهِ وَسَنَةً أُخْرَى بِكَذَا وَكَذَا قَالَ لاَ بَأْسَ بِهِ وَيُجْزِئُهُ اشْتِرَاطُكَ حِينَ تُؤَاجِرُهُ أَيَّامًا أَوْ آجَرْتَهُ وَقَدْ مَضَى بَعْضُ السَّنَةِ قَالَ إِنَّكَ لاَ تُحَاسِبُنِي لِمَا مَضَى