Musannaf Ibn Abi Shayba 1:924

Hushaym narrated to us, he said: Hajjaj and Ibn Abi Layla narrated to us, from ‘Ata’, from Ibn ‘Abbas, regarding seminal impurity (janabah) that gets on a garment. He said: "It is only like phlegm or saliva; remove it from yourself with a rag or with lemon grass."