The 24-year-old batsman was floored after turning his back on a brutish delivery from the paceman.
It looked certain that he would be forced to retire hurt but he was on his feet surprisingly quickly. Hashmatullah said those who attended him in the middle instructed him to leave the field but he opted to stay in place, adding another 52 runs after the incident to top score with 76.
Runs on the board are unlikely to persuade those who feel cricket can be too lax in its approach to concussion and head injuries, but there was no denying the emotional weight of Hashmatullah's explanation.
"I got up early because of my mum," he said.
"One of the reasons I got up so quickly is because my mum is always thinking of me. I lost my father last year so I didn't want her to hurt. My whole family was watching, even my big brother was here in the ground watching. I didn't want them to be worried for me."
Those are admirable sentiments from a plucky cricketer, but the remainder of his account offered reason for concern.
"The ICC doctors came to me, and our physios, and my helmet was broken in the middle," he recalled.
"They just told me just, 'let's go'. I told them I can't leave my team-mate at that moment. My team needed me, I carried on.
"After the match I went to the ICC doctor and talked to them. They took care of me and said it will be fine, inshallah."
A team official, Naveed Sayeh, confirmed Hashmatullah had acted against advice in continuing his innings.
He said: "The doctors told him, 'please come off' and to leave the ground. He told them, 'no, I'm now OK so I'll continue my batting'."
Hashim Amla returned to the crease in the tournament's opening fixture after being hit on the helmet by England's Jofra Archer only to be subsequently ruled out of the following fixture with concussion.
Afghanistan captain Gulbadin Naib earlier pleaded ignorance when asked about a reported incident at a Manchester restaurant the night before the game.
A confrontation is alleged to have taken place with a member of the public at a curry house, but had no information to offer.
"No, I haven't, so you can ask my security officer. I didn't know anything about him, about them," he said.
"It's not a big issue for the team, for me."
A statement released by Greater Manchester Police read: "Shortly after 11.15pm on Monday 17 June 2019, police were called to reports of an altercation at a premises on Liverpool Road in Manchester.
"Officers attended the scene. No one was injured and no arrests have been made. Enquiries are ongoing."
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