Kharijah bin Zayd bin Thabit narrates that Sayyiduna Zayd bin Thabit (may Allah be pleased with him) told him that the Messenger of Allah (peace and blessings be upon him) used to lengthen the recitation in Zuhr and Asr and would move his lips, and I knew that he (peace and blessings be upon him) moved his lips only for the recitation.
Hadith Referenceالمعجم الكبير للطبراني / باب الزاي / 4867