It is narrated from Sayyiduna Sahl bin Hunayf (may Allah be pleased with him) that he asked the Prophet (peace and blessings be upon him) about madhi (pre-seminal fluid), and he (peace and blessings be upon him) said: "Ablution alone is sufficient for you for it." He said: What should I do if it gets on my garment? He (peace and blessings be upon him) said: "Take a palmful of water and sprinkle it on your garment where you think it has touched."
Hadith Referenceالمعجم الكبير للطبراني / باب السين / 5572