This same report is narrated through another chain, with the addition that Mujahid (may Allah have mercy on him) narrates from Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both): Dawud (peace be upon him) was also among those (guided) people whom your Prophet (peace and blessings be upon him) was commanded to follow; but it does not mention the practice of Sayyiduna Ibn Abbas (may Allah be pleased with them both).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 3748