كتاب الصلاة
4  
The Book of Prayers
(45)
Chapter: Moderation In Prostration; Placing The Hands On The Ground, Keeping The Elbows Up, Away From The Sides, And Lifting The Belly Up Off The Thighs When Prostrating
(45)
باب الاِعْتِدَالِ فِي السُّجُودِ وَوَضْعِ الْكَفَّيْنِ عَلَى الأَرْضِ وَرَفْعِ الْمِرْفَقَيْنِ عَنِ الْجَنْبَيْنِ وَرَفْعِ الْبَطْنِ عَنِ الْفَخِذَيْنِ فِي السُّجُودِ
Sahih Muslim 493 b

This hadith has been narrated by Shu'ba with the same chain of transmitters. And in the hidith transmitted by Ibn Ja'far (the words are):

" None of you should stretch out his forearms like the stretching out of a dog."
حَدَّثَنَا مُحَمَّدُ بْنُ الْمُثَنَّى، وَابْنُ، بَشَّارٍ قَالاَ حَدَّثَنَا مُحَمَّدُ بْنُ جَعْفَرٍ، ح قَالَ وَحَدَّثَنِيهِ يَحْيَى بْنُ حَبِيبٍ، حَدَّثَنَا خَالِدٌ، - يَعْنِي ابْنَ الْحَارِثِ - قَالاَ حَدَّثَنَا شُعْبَةُ، بِهَذَا الإِسْنَادِ وَفِي حَدِيثِ ابْنِ جَعْفَرٍ ‏ "‏ وَلاَ يَتَبَسَّطْ أَحَدُكُمْ ذِرَاعَيْهِ انْبِسَاطَ الْكَلْبِ ‏"‏ ‏.‏
Reference : Sahih Muslim 493b
In-book reference : Book 4, Hadith 265
USC-MSA web (English) reference : Book 4, Hadith 998
  (deprecated numbering scheme)