It is narrated from Hisham bin Sa'd: I heard Nafi' say that Abdullah bin Umar (may Allah be pleased with them both) saw a man praying, slumped on his knees and leaning on his left hand, and he said: "Do not pray like this; it is those who are being punished who sit like this."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2811