Reading Hajime Nakamura's Translation of Buddha's Words: Listening to the Buddha's Words
One of the oldest sutras, the Buddha's Words ("Sthanipata") is said to be the closest to the teachings actually preached by the Buddha at the time of his death.
This sutra, "Buddha's Words," is simple but deeply resonant.
The famous phrase "Walk alone like a rhinoceros horn" is also taught in this sutra. It is also my favorite sutra.