Musannaf Ibn Abi Shayba 3:2339

Waki’ narrated to us, he said: Sufyan narrated to us, from ‘Asim ibn Abi al-Najud, from al-Musayyab ibn Rafi’, who said: ‘Abdullah said: "Four things are from rudeness: that a man prays without a sutrah (barrier), that he wipes his forehead before he finishes (the prayer), or that he urinates while standing, or that he hears the caller (to prayer) and does not answer him."