It is narrated from Ata bin Abi Rabah (may Allah have mercy on him) that the Messenger of Allah (peace and blessings be upon him) said: "When you drink, drink by sipping, and when you use the siwak, use it crosswise."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 175
Hadith Gradingمحدثین:ضعيف أخرجه اوب داؤد في المراسيل