Medicine Buddha Sutra or Bhaiṣajyaguruvaidūryaprabharāja Sūtra
This Mahayana text is about Bhaisajyaguru, who upon achieving Buddhahood became the Buddha of the Eastern lands. His teachings are considered medicine for the problems of our life.
You will often hear the Mantra of the Medicine Buddha chanted during chanted meditation at temples and many will do so at home as well.
namo bhagavate bhaiṣajyaguru
arhate samyaksambuddhāya tadyathā:
oṃ bhaiṣajye bhaiṣajye mahābhaiṣajya-samudgate svāhā.