JD Davison was working out at the Celtics’ practice facility Saturday when Brad Stevens approached him. He wanted to have a chat with the third-year point guard.

Stevens had come to inform Davison that his three years of toiling on two-way contracts, which included 142 games in the G League, had paid off. The Celtics were converting his contract to a standard NBA deal to fill their final 15-man roster spot ahead of the playoffs.

“The work I put in is, it’s working,” a smiling Davison said before Sunday’s regular-season finale against the Charlotte Hornets. “Trusting in God, and the prayers worked.”

Davison was “definitely surprised” by his promotion — “to get a contract with the Boston Celtics, one of the best teams in the league, it’s not easy” — but believed he “put everyone on notice” by dominating the G League this season. He was the Most Valuable Player of the NBA’s farm circuit, starring for a Maine Celtics team that fell one win short of the G League finals.

“It’s not easy, man, especially playing in the G League for three years,” said Davison, who is Maine’s all-time leader in points, assists, steals and games played. “It’s not easy to stay the course, but I feel like I stayed down, I stayed the course. I just kept my head down, put in the work and trusted God, and then finally came true.”

Davison said his mother, Katrina, cried when he told her the news.

“I know my mom, I know she’s been praying about it every day,” he said. “I know she’s probably at church praying about it. Just knowing her, I know she’s super proud. I know everyone back home (in Lowndes County, Ala.) is super proud. So just knowing that I’ve got them behind me, they just tell me to keep going and it’s going to be all right.”

With three established guards above him on the depth chart in Derrick White, Jrue Holiday and Payton Pritchard, the 6-foot-1 Davison has seen very little NBA playing time in his pro career, totaling just 181 minutes over 35 appearances for Boston. That’s not likely to change this postseason, barring a rash of injuries.

Though Davison almost certainly will watch the bulk of Boston’s playoff run from the bench, Celtics head coach Joe Mazzulla believed his addition to the roster was a fitting reward for his efforts.

“I think just validation of the work and the patience and the time from the years that he’s been with us,” Mazzulla said. “It’s obviously easier to see the on-court development and how he’s gotten better, but I think he’s gotten better off the floor as far as his leadership, his communication, his growth, his maturity, which, coming into the league at a young age, that’s something that’s going to be tested. I just thought it was the right thing to do because of what he’s done for our program and what he’s done as a player and what he’s done as a person off the court. So I’m really happy for him.”