In whatever you do, you must uphold your original belief. Only in this way will you be able to succeed in the end.
Source: "Only by not forgetting the original intention can you achieve success" is interpreted in some verses of the "Huayan Sutra", and there is no original sentence. After the interpretation, the language is popular and the truth is straightforward. Most people will be touched after seeing it, so the sayings from the Avatamsaka Sutra spread.
Original text of "The Avatamsaka Sutra":
Volume 17 of "The Avatamsaka Sutra of the Great Expanse Buddha": All Tathagatas in the three generations have not protected the initial intention of thinking. Volume 19 of "Dafang Guangfo Huayan Sutra": Just like the original intention of a Bodhisattva, it is not the same as the later intention.
Extended information
From the perspective of Buddhism, Taoism and Confucianism, the original intention is the truth, the soul, the heart, and the innocent heart. The so-called heart and thoughts are all obedient (a child being obedient means being obedient, being controlled, that is, being attached), that is, attachment and delusional thoughts (also called delusional minds), so the "Laojun Chang Jing Jing Jing" states: To have delusional minds, that is Living with greed, troubles and delusions, suffering physically and mentally, wandering in life and death, often sinking into the sea of ??suffering.
The so-called forever means that there is a beginning and an end, that is, perfection. Therefore, only by not forgetting the original intention can we achieve success. From the perspective of Confucianism, Buddhism and Taoism, it means: not losing or forgetting the original intention, and living in the true nature is the perfect state. That is to say, "Lao Jun's Sutra of Always Purity": If a person can always be pure, all heaven and earth will return. He should always be quiet and always pure. From a life perspective, it means: don’t lose sight of your original goal, consistently maintain your original belief, and you will definitely succeed in the end.