Yahya bin Sa'id al-Ansari narrates that when Sayyiduna Abu Bakr (may Allah be pleased with him) sent Sayyiduna Yazid bin Abi Sufyan (may Allah be pleased with him) to Syria, he walked along with him on foot. Yazid (may Allah be pleased with him) said to him: "Either you ride, or I will dismount." He said: "I will not ride, and you will not dismount; I count these steps of mine for reward before Allah."
Hadith Referenceالمعجم الكبير للطبراني / باب الياء / 18827