A.T. Robertson Commentary Mark 15:21

"And they compel one passing by, Simon of Cyrene, coming from the country, the father of Alexander and Rufus, to go [with them], that he might bear his cross." — Mark 15:21 (ASV)

They compel (αγγαρευουσιν). Dramatic present indicative again where Mt 27:32 has the aorist. For this Persian word see on Mt 5:41; 27:32.

Coming out of the country (ερχομενον απ' αγρου). Hence Simon met the procession. Mark adds that he was "the father of Alexander and Rufus." Paul mentions a Rufus in Ro 16:13, but it was a common name and proves nothing. See on Mt 27:32 for discussion of cross-bearing by criminals. Luke adds "after Jesus" (οπισθεν του Ιησου). But Jesus bore his own cross till he was relieved of it, and he walked in front of his own cross for the rest of the way.