A mantra (Pali; manta) is a sound or a combination of sounds used as a spell. Hinduism at the time of the Buddha taught that repeating certain mantras would impart spiritual power and blessings and evoke the help of the gods.
Some mantras consist of a single syllable (bīja mantra) while others are quite long. The Buddha rejected the efficacy of mantras as he did all forms of magic and replaced it with the idea that the greatest strength and protection comes from having a pure mind. In the Jātaka there is a story he told about a group of virtuous men who were falsely accused of doing wrong and were sentenced to be trampled by elephants. But try as he might, the executioner could not get the elephants to kill the men. Assuming that they must be reciting some protective spell or incantation the executioner asked them; 'What is your mantra?' The leader of the men replied; 'We have no mantra other than this, that none of us kills, steals, sexually misconducts ourselves exploits, lies or drinks alcohol. We cultivate love, practise generosity, repair roads, construct watering holes and built rest houses for travellers. This is our mantra, our protection and the thing by which we flourish' (Ja.I,200).
- http://www.BuddhismA2Z.com/ Buddhism A to Z. Ven. Dhammika, 2007.