Prostration and its Excellence - Section 1 Mishkat al-Masabih 888
Arabic hadith text
وَعَنْ أَنَسٍ قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «اعْتَدِلُوا فِي السُّجُودِ وَلَا يَبْسُطْ أَحَدُكُمْ ذِرَاعَيْهِ انْبِسَاطَ الْكَلْبِ»
Translation
Anas reported God’s Messenger 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.” (Bukhari and Muslim.)