Musannaf Ibn Abi Shayba 13:2789

Abu Bakr narrated to us, he said: Abdullah ibn Idris narrated to us, from Yahya ibn Sa'id, from 'Awn ibn 'Ubayd Allah ibn Abi Rafi', from 'Ubayd Allah ibn 'Abd Allah ibn 'Umar, he said: 'Umar said: "When the boundaries are established and people know their rights, there is no pre-emption (shuf'ah) between them."