Abu al-Jahm Subayh bin al-Qasim (may Allah have mercy on him) says: I made a kitabah contract for 20 thousand on condition that I would not leave Kufah. I asked Sa'id bin al-Musayyab (may Allah have mercy on him), and he said: "20 thousand, and the earth has been made narrow for you as well? Travel." And Sa'id bin Jubayr (may Allah have mercy on him) said the same.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب المكاتب / 21695