Hanina ben Dosa was the most famous miracle worker in all of rabbinic literature, and his signature miracle was healing the sick — not with medicine, not with herbs, not with any physical remedy at all, but with prayer alone.
The Talmud in Berakhot (34b) records the most celebrated instance. Rabban Gamliel's son fell dangerously ill. Desperate, Rabban Gamliel sent two of his students to Hanina ben Dosa with a plea for help. When the students arrived, Hanina went up to an upper room, prayed, and came back down. "Go home," he told them. "The fever has left him."
The students were skeptical. "Are you a prophet?" they asked. Hanina's answer was characteristically modest. "I am neither a prophet nor the son of a prophet. But I have a tradition: if the prayer flows smoothly from my mouth, I know it has been accepted. If it stumbles, I know it has been rejected." On this occasion, the prayer had flowed like water.
The students noted the exact time and returned to Rabban Gamliel's house. The sick boy had recovered at precisely the moment Hanina had finished his prayer. Not approximately. Not close to that time. At that exact moment, the fever broke and the boy sat up and asked for food.
The Jerusalem Talmud (Berakhot V:5) adds that this was not a one-time event. Hanina ben Dosa healed multiple people in exactly the same way — through the sheer force of his connection to God. He owned almost nothing. He lived in grinding poverty. His wife once lit the Sabbath candles with vinegar because they had no oil. But his prayers could reach across miles and pull a dying person back from the edge.
The medieval folk tradition treasured Hanina ben Dosa above almost any other sage — not for his learning, which was modest, but for his proof that a pure heart can move heaven.