Sahih Muslim
The Book of Mosques and Places of Prayer
Hadith #118
5.118
وَحَدَّثَنَاهُ ابْنُ أَبِي عُمَرَ، حَدَّثَنَا عَبْدُ الْعَزِيزِ بْنُ عَبْدِ الصَّمَدِ، عَنْ مَنْصُورٍ، بِإِسْنَادِ هَؤُلاَءِ وَقَالَ " فَلْيَتَحَرَّ الصَّوَابَ " .
This hadith has been narrated by Mansur and he said:" He should aim at correctness