Authentic Supplication Number 146.

Abu Sa`eed ‘Al-Khudriy  said: A small number of the companions of the Prophet  took off in one of their journeys till they reached an Arab tribe. Then they asked hospitality of them, whereupon, they refused to show them hospitality. The chief of the town was soon after bitten [by a scorpion or a snake]. They sought everything for him; however nothing did him any good. Then a few of them said: Why don’t you go to that group of men that have taken lodging over there? Perhaps some of them might have something [for it]. So they went to them and said: O’ you folk, our chief has been stung and we tried everything but nothing did him any good, so does anyone of you have something [to treat him with]? One of them then said: By Allah I charm; however, by Allah we asked you to show us hospitality, and you refused, so I am not going to charm for you until you set an agreed upon price. They then reconciled over a flock of sheep. Then the man set off spitting on him [on the chief], and reciting ‘Al-hamdu lil-lahi rabbil alameena (165).

It was then as if he had been set free after having been all tied up, he started walking without any pain. [He said:] So they gave them what they had agreed upon. Some of them (or one of them) then said: Split [the flock], the charmer then said: No do not, not until we come upon the Messenger of Allah  and tell him about what happened [we will see what he orders]. So they came to the Messenger of Allah  and told him, he then said: “And what makes you know it to be a charm?” Then he said: “You have struck correctly, so do split [the flock] and cast me a share along with you.” The Prophet then laughed.

(165) May be translated as: All praise to Allah the Lord of the Worlds.

Agreed upon by Bukhari and Muslim. Al-Albani included this hadeeth in The Authentic of Good Sayings as #117.