It was narrated from Hammad and Qatadah, concerning a man who said to another man:
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.