Sunan an-Nasa'i 3861
It was narrated that Ibn Juraij said:
"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.'"
أَخْبَرَنَا مُحَمَّدُ بْنُ حَاتِمٍ، قَالَ أَنْبَأَنَا حِبَّانُ، قَالَ أَنْبَأَنَا عَبْدُ اللَّهِ، عَنِ ابْنِ جُرَيْجٍ، قِرَاءَةً قَالَ 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.‏‏