Musannaf Ibn Abi Shayba 1:1492

Zajir ibn al-Salt narrated to us, from al-Harith ibn Malik, who said: I went to the house of al-Hasan. A man came to him and asked him, saying: "O Abu Sa'id, a man scratches either his body or his arms, then he puts his saliva on it and wipes it over it; does he have to perform ablution (wudu) from that?" He said: "No."