How sound are the narrations that speak of the Companions racing to [collect] the saliva (sputum) of the Noble Prophet, peace and blessings be upon him?

Al-Bukhari narrated in the story of Al-Hudaybiyyah that Urwah ibn Mas'ud said to Quraish: "By Allah, I have never seen a king whose companions revere him as much as the companions of Muhammad (peace be upon him) revere Muhammad. By Allah, he does not spit any phlegm but it falls into the palm of one of them, who then rubs it on his face and skin." Some scholars mentioned that the Companions did this on that day to show his greatness and to respond to Urwah's statement to the Prophet (peace be upon him): "Indeed, I see a rabble of people who are likely to flee and abandon you."