Language:
كتاب الصلاة
8
Prayers (Salat)
(66)
Chapter: While passing through a mosque, (one should better) hold the arrowheads (with the hand)
(66)
باب يَأْخُذُ بِنُصُولِ النَّبْلِ إِذَا مَرَّ فِي الْمَسْجِدِ
Sahih al-Bukhari 451

Narrated `Amr:

I heard Jabir bin `Abdullah saying, "A man passed through the mosque carrying arrows. Allah's Apostle said to him, 'Hold them by their heads.' "

حَدَّثَنَا قُتَيْبَةُ بْنُ سَعِيدٍ، قَالَ حَدَّثَنَا سُفْيَانُ، قَالَ قُلْتُ لِعَمْرٍو أَسَمِعْتَ جَابِرَ بْنَ عَبْدِ اللَّهِ يَقُولُ مَرَّ رَجُلٌ فِي الْمَسْجِدِ وَمَعَهُ سِهَامٌ، فَقَالَ لَهُ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏ "‏ أَمْسِكْ بِنِصَالِهَا ‏"‏‏.‏
Reference : Sahih al-Bukhari 451
In-book reference : Book 8, Hadith 100
USC-MSA web (English) reference : Vol. 1, Book 8, Hadith 442
  (deprecated numbering scheme)