The 31-year-old Rask said only that the leave was due to a family matter.
"I have a job. My job is to be a hockey goalie for the Boston Bruins, and I also have another job title and that's a family man," Rask said, according to NHL.com. "And this was a time when deep inside my heart I felt like I needed to take time to be with my family and make things right so I can be back here and focus on my job. That took three days. I'm back here. I'm back to work. And I'm ready to battle with these guys.
"At the end of the day, I realized that a hockey career is a very short career but your life is much longer than that. I appreciate that I got the privacy and time I needed. I'm ready to move on now."
Rask has started only seven of the Bruins' 15 games this season and acknowledged having been outplayed recently by Jaroslav Halak.
Rask came on in relief in the Bruins' 8-5 loss to the Vancouver Canucks on Thursday night. Halak was pulled after allowing five goals on 19 shots. Rask allowed three goals on the first eight shots he faced.
The Bruins next face the Avalanche on the road Wednesday. Coach Bruce Cassidy said that Rask will start either Friday at Dallas or Saturday at Arizona.
Rask, who has a 3.05 goals-against average and .901 save percentage to Halak's 1.77 and .945, isn't blaming his slow start on personal matters.
"It hasn't affected my job," he said, according to NHL.com. "I'm not going to make excuses that I played good games or bad games because of my personal life."
Rask thanked the organization for giving him the opportunity to settle his matter.
"I've never been more proud to be a part of this family, the Boston Bruins," he said.
Information from The Associated Press was used in this report.