I say, and with God's success: Yes, this is established, and among it is what was reported from Umm al-Fadl bint al-Harith: "That some people disputed with her on the Day of Arafah about the fasting of the Prophet (peace be upon him); some said: He is fasting, and some said: He is not fasting. So she sent to him with a cup of milk while he was standing on his camel, and he drank it." This was narrated by Al-Bukhari (1988) and the wording is his, and Muslim (1123). There was a reason for this, whether due to illness or travel, or to indicate that it is recommended so that it does not become obligatory upon his nation. For further benefit, refer to Tuhfat al-Ahwadhi (3/385), and God knows best.