EVEN VOWS THAT HAVE NOT BEEN FULFILLED HAVE KARMIC REWARDS
Master Jun Hong Lu: One must understand the importance of the power of vows. Ksitigarbha Bodhisattva has once vowed, “To not become a Buddha until all hells are emptied”. Although hells have not been emptied, the power of His vows has helped Him accomplish His current attainment. Why is it that even if the vow has yet to be fulfilled, there are still karmic rewards?
Take for instance, you are very sincere in wanting to complete a task. You may not succeed in your quest, but your outright willingness to do so is meritorious in itself and is contingent upon you making a great vow. In addition, the moment you give rise to the great spirit of giving, virtue and with a strong determination, coupled with immense compassion, your spirit will gradually be cleansed and in the process, your spirit will be purified.
The purity of your innate nature will reveal itself once it is free from impurities. Over time, you will be detached from the defilements of the realm of desires. As you slowly go through this purification process, over time, your state of mind will transcend the realm of desires.
Source: Master Jun Hong Lu’s Buddhism In Plain Terms, Volume 2 Chapter 33