Sahih Muslim
The Book of Mosques and Places of Prayer
Hadith #116
5.116
حَدَّثَنَاهُ مُحَمَّدُ بْنُ الْمُثَنَّى، حَدَّثَنَا مُحَمَّدُ بْنُ جَعْفَرٍ، حَدَّثَنَا شُعْبَةُ، عَنْ مَنْصُورٍ، بِهَذَا الإِسْنَادِ وَقَالَ " فَلْيَتَحَرَّ أَقْرَبَ ذَلِكَ إِلَى الصَّوَابِ " .
This hadith has been narrated by Mansur with the same chain of transmitters and said:" He should aim at correctness and that is right