Hafs bin 'Umar bin al-Harith حفص بن عمر بن الحارث · Wages (Kitab Al-Ijarah)

When the Messenger of Allah (ﷺ) came to Medina, they were paying one, two and three years in advance for fruits, so he said: Those who pay in advance for anything, must do for a specified measure and weight with a specified time fixed.