Nachum Ish Gamzu was a Tanna of the second generation, living in the first century. He was one of the teachers of Rabbi Akiva, who according to tradition served him for twenty-two years. He is best known for his saying "Gam zu letovah", "this too is for the best", which he repeated in the face of every hardship.

The Talmud (Taanit 21a) explains that his name came from this habit. Rabbeinu Chananel and Rabbi Nathan of Rome, in the Arukh, explain it instead as the name of his town, Gimzo, a place in Judea mentioned in the Book of Chronicles.

The Talmud relates that he was sent to the emperor with a chest of precious stones, which was robbed during the night and filled with earth. Facing the ruler's anger, he said, "This too is for the best." According to the account, Eliyahu appeared as one of the officials and suggested that this was perhaps the earth of Avraham, which turned into swords; it was tried against a province that could not be conquered, the province fell, and Nachum returned laden with honors.

According to the same passage, at the end of his life he was blind, without the use of his hands and feet, and covered with boils. When his students asked why, he explained that he had brought these sufferings upon himself after a poor man, whom he had asked to wait while he unloaded his donkey, died before receiving food. In interpreting the Torah he applied the rule of inclusion and exclusion (ribbui u-miut), which, according to the Tosefta, Rabbi Akiva learned from him.

One tradition places his grave in Safed, on Gamzu Street in the southern part of the town, where the city holds his hillula on 15 Av; another tradition places it on the road to Parod.