Musannaf Ibn Abi Shaybah 9403 — Those who permitted the siwak

Khusayf said: Ata said: "When you are fasting, use the siwak in the early part of the day, and do not use the siwak in the latter part of the day." I said: "Why should I not use the siwak in the latter part of the day?" He said: "The smell of the fasting person's mouth is more pleasing to Allah than the fragrance of musk."