Sunan Abi Dawud 897
سنن أبي داود#897Sahihحَدَّثَنَا مُسْلِمُ بْنُ إِبْرَاهِيمَ، حَدَّثَنَا شُعْبَةُ، عَنْ قَتَادَةَ، عَنْ أَنَسٍ، أَنَّ النَّبِيَّ صلى الله عليه وسلم قَالَ " اعْتَدِلُوا فِي السُّجُودِ وَلاَ يَفْتَرِشْ أَحَدُكُمْ ذِرَاعَيْهِ افْتِرَاشَ الْكَلْبِ " .
Anas reported the Messenger of Allah(ﷺ) as saying; Adopt a moderate position when prostrating yourselves, and see that none of you stretches out his forearms(on the ground) like a dog
Scholarly Authentication
The label above is the grade most of these scholars gave — one dissenting opinion no longer speaks for all of them. If any scholar calls a narration fabricated, that verdict is shown instead, whatever the others say. Each scholar's own wording:
Al-AlbaniSahih
Muhammad Muhyi Al-Din Abdul HamidSahih
Shuaib Al ArnautSahih
Zubair Ali ZaiSahih Bukhari (822) Sahih Muslim (494)
In-book reference: 2:507