It is narrated from Sayyiduna Ibn Umar (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings be upon him) said: "Offer the funeral prayer over whoever says La ilaha illallah (there is no god but Allah), and pray behind whoever says La ilaha illallah."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 13565