Rabi'a ibn 'Abdullah ibn al-Hadir ibn 'Abdullah reported tht two men wagered two cocks in the time of 'Umar. 'Umar ordered that the cock be killed and a man of the Ansar said to him, "Will you kill a something which glorifies Allah?" So 'Umar left it.  

أَنَّ رَجُلَيْنِ اقْتَمَرَا عَلَى دِيكَيْنِ عَلَى عَهْدِ عُمَرَ فَأَمَرَ عُمَرُ بِقَتْلِ الدِّيَكَةِ فَقَالَ لَهُ رَجُلٌ مِنَ الأَنْصَارِ أَتَقْتُلُ أُمَّةً تُسَبِّحُ؟ فَتَرَكَهَا