The Bodhisatta was once a king. Another king conquered the city and killed him. His queen was taken to be a wife of the new king, though the Bodhisatta’s son escaped. The son raised an army and soon returned to fight, but his mother sent a message that he should lay siege to the city instead of attacking. He took her advice and after seven days of no water, firewood, and food getting inside, the angry citizens cut off the king’s head and brought it to the son, who took the throne.
In the Lifetime of the Buddha
One of the king’s daughters carried a child in her womb for seven years and was in the midst of painful labor for seven days. She was a loyal supporter to the Buddha and sent her husband to give him a greeting since she had not seen him for a long time. The Buddha gave a blessing for a healthy child and at these words her son was born. Following this, she honored the Buddha with seven days of hospitality and during this time, Sariputta, one of the Buddha’s top disciples, asked the boy how he felt and he answered, “Not great since I had to wallow in blood for seven long years.” When the boy reached age seven, he became a novice under the Buddha and a full disciple at age twenty, and through his righteousness became an arahant.
The son who became king and his mother were earlier births of this child and his mother. One day when the Buddha heard some disciples discussing the seven-year pregnancy, he told them this story so they knew it was a result of the boy and his mother blockading the city in past lives.