Sayyiduna Ibn Umar (may Allah be pleased with them both) narrates it as mawquf (as his own statement).
It has also been narrated from Atiq bin Ya'qub, from Malik, from Nafi', as marfu' (attributed to the Prophet), but the correct view is that it is mawquf.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 1743