Metta-Sutta(p)—Maitri-Sutra (skt)—Sutra on Kindness composed by the Hinayana school. It is one of the most popular texts of the Theravada and recited daily by monks, nuns and lay people in this school. The texts says:
This is what should be done by a man who is wise, who seeks the good, and know the meaning of the place of peace. Let him be strenuous or determined, upright, and truly straight. Let him not be submerged by the things of the world, let him live a simple life and easily contented and joyous—Let his sense be controlled. Let him not desire great possessions even for his family. Let him do nothing that is mean or that the wise would reprove. May all beings be happy and at their ease! May they be joyous and live in safety! All beings whether weak or strong, in high, middle or low realms of existence, small or great, visible or invisible, near or far away, born or to be born—May all beings be happy at their ease! Let none deceives another, or despites any beings in any states! Let none be anger or ill-will wish harm to another! Even as a mother watches over and protects her child, her only child , so with a boundless mind should one cherish all living beings, radiating friendliness over the entire world, above, below, and all around without limit. So let him cultivate a boundless good will towards the entire world, uncramped, free from ill-will or enmity. Standing or walking, sitting or lying down, during all his walking hours, let him establish this mindfulness of goodwill, which men call the highest state. Abandoning vain discussions, having a clear vision, free from sense appetites, he who is made perfect will never again know rebirth.