حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا وَكِيعٌ، عَنْ شُعْبَةَ، عَنْ قَتَادَةَ، عَنْ أَنَسٍ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏"‏ اعْتَدِلُوا فِي السُّجُودِ وَلاَ يَبْسُطْ أَحَدُكُمْ ذِرَاعَيْهِ انْبِسَاطَ الْكَلْبِ ‏"‏ ‏.‏

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."