(R. Simon citing R. Yehoshua ben Levi, and R. Yosi ben Sha'ul citing Rebbi): One who despairs from his slave may not force him to serve him. He must write a Get Shichrur for him.

R. Yochanan heard this, and said 'R. Yehoshua ben Levi taught us well! We learned a Get Shichrur only from [divorce] of a woman. Just like a woman does not leave [her husband] due to despair, rather, she needs a Get, also a slave does not leave due to despair, and he needs a Get Shichrur.

(Shimon bar Ba citing R. Yochanan): If a slave fled from captors to his master, he may not force him to serve him, and he must write a Get Shichrur for him.

(R. Avahu citing R. Yochanan): One who is Mafkir his slave, he may not force him to serve him, and he need not write a Get Shichrur for him.

Question (R. Ze'ira, to Shimon bar Ba): Everyone says that he must [write a Get Shichrur for him], and you say that he does not need?!

Suggestion: Perhaps [Shimon bar Ba] means that [if the slave is Arel, even without a Get Shichrur] he does not stop [his master] from eating [Korban] Pesach;

This is like it was taught "v'Chol Eved Ish Miknas Kesef u'Maltah Oso" - when [a slave must] serve his master, he stops him from eating Pesach, but when he [need] not serve his master, he does not stop him from eating Pesach.