Albert Barnes on Matthew 11:28

All ye that labour and are heavy laden. He here, perhaps, refers primarily to the Jews, who groaned under the weight of their ceremonial laws, and the traditions of the ciders, Acts 15:10. He tells them, that by coming to him, and embracing the new system of religion; they would be freed from these burdensome rites and ceremonies. There can be no doubt, however, that he meant here chiefly to address the poor, lost, ruined sinner; the man burdened with a consciousness of his transgressions, trembling at his danger, and seeking deliverance. For such there is relief. Christ tells them to come to him, to believe in him, and to trust him, and him only, for salvation. Doing this he will give them rest--rest from their sins; from the alarms of conscience; from the terrors of the law; and from the fears of eternal death.

(c) "labour" Is 55:1-4