The Sabres retained 50% of Hall's salary, according to TSN's Pierre LeBrun.
Hall was one of the most coveted forwards on the market ahead of Monday's trade deadline. He's notched two goals and 17 assists in 37 games this season. The 29-year-old inked a one-year deal with the Sabres during the offseason with a value of $8 million.
The former Hart Trophy winner has racked up 220 goals and 362 assists in 664 career games with the Edmonton Oilers, New Jersey Devils, Arizona Coyotes, and Sabres. This marks the third time he's been traded in his career.
Lazar has five goals and four assists in 33 contests. He's been out of the lineup recently with a lower-body injury he suffered on March 31.
Bjork, 24, has collected two goals and three assists in 30 games with the Bruins this season. Previously selected in the fifth round by Boston in 2014, he's totaled 16 goals and 23 assists in 138 career games.