Not always true.
As an example, there is a an old story of a monk who was meditating happily in the sun outside his cave when a beautiful but very distressed damsel came running up to him. “Help me,” she cried. “There’s a very bad man, a robber, who is trying to kill me. Please, let me hide in your cave.” Without waiting for a reply, the girl ran into his cave and hid in the dark interior. The monk had not said a word and, although slightly perturbed, he continued to meditate. A few minutes later a wild-looking man with a patch on one eye came galloping up on a black horse. When he saw the monk, he stopped and yelled at him, “Have you seen a young woman? I must find her.” Being a celibate, the monk quite calmly said to the robber, “What would I be doing with a woman?” To which the man galloped on.
The monk did not lie, nor did he honestly answer the question. However, by avoiding the truth he saved three lives: the girl’s; his own, as the robber would have had to kill him for being a witness; and the robber’s, who would have been killed as punishment.
Everything we think, say and do has an immediate effect on everyone around us. This means that our words and actions can lead to chaos and destruction as easily as they can lead to healing and friendship. So it would seem that sometimes avoiding the truth or maybe watering it down can be the more moral and compassionate act. A white lie can save a situation from getting badly out of hand.
With this awareness, we are able to discern between times when actions and words are either skillful or unskillful, where we are being a help or a hindrance. Skillful action brings out the best in each situation, such as harmlessness and generosity, while unskillful actions maintain and reinforce separation; they are basically harmful and self-centered. Their primary concern is protecting the “me.”
But while there are bad lies that are destructive and self-centered, there are also good lies that serve to not cause harm.
http://www.huffingtonpost.com/ed-and-deb-shapiro/when-telling-a-lie-is-right_b_841017.html
This story is repeated in various Avatars by different storytellers.