Sahih al-Bukhari 2264
Sahih al-Bukhari · Book 37: Hiring · It is legal if somebody hires someone to work for him after three days, or after one month or after a year. When that period elapses they should carry out their contract
Narrated Aisha:
حَدَّثَنَا يَحْيَى بْنُ بُكَيْرٍ ، حَدَّثَنَا اللَّيْثُ ، عَنْ عُقَيْلٍ ، قَالَ ابْنُ شِهَابٍ فَأَخْبَرَنِي عُرْوَةُ بْنُ الزُّبَيْرِ ، أَنَّ عَائِشَةَ ـ رضى الله عنها ـ زَوْجَ النَّبِيِّ صلى الله عليه وسلم قَالَتْ وَاسْتَأْجَرَ رَسُولُ اللَّهِ صلى الله عليه وسلم وَأَبُو بَكْرٍ رَجُلاً مِنْ بَنِي الدِّيلِ، هَادِيًا خِرِّيتًا وَهْوَ عَلَى دِينِ كُفَّارِ قُرَيْشٍ، فَدَفَعَا إِلَيْهِ رَاحِلَتَيْهِمَا، وَوَاعَدَاهُ غَارَ ثَوْرٍ بَعْدَ ثَلاَثِ لَيَالٍ بِرَاحِلَتَيْهِمَا صُبْحَ ثَلاَثٍ.
(the wife of the Prophet) Allah's Messenger (ﷺ) and Abu Bakr hired a man from the tribe of Bani-Ad-Dil as an expert guide who was a pagan (follower of the religion of the pagans of Quraish). The Prophet (ﷺ) and Abu Bakr gave him their two riding camels and took a promise from him to bring their riding camels in the morning of the third day to the Cave of Thaur.