Srimad Bhagavad Gita with the commentary of Sri Adi Sankaracharya translated into English by Swami Gambhirananda. Adi Sankara's is probably the earliest extent commentary on the Bhagavad Gita. The text of the Gita as cited by him has come down the centuries as the authentic text and this commentary of his has proved to be of seminal value ever since. Later commentators may differ from him on textual and even metaphysical interpretation but the spiritual well-being flowing into us on reading the Gita-Bhasya of Sankaracharya is universally acknowledged. One has only to read it to feel it.