Sahih Muslim
The Book of Drinks (Kitab Al-Ashriba)
Book Number: 023 / Hadith Number: 5001
This hadith is reported on the authority of Laith b. Sa'd with the same chain of transmitters, but with a slight variation in wording (and that is that) he (the Holy Prophet) said: There is a day in a year when descends the pestilence; at the end of the hadith Laith said that the non Arabs save themselves from it in Kanun Awwal (this is the month of December).