Every single letter in the Torah has meaning, whether by its addition or subtraction. The Torah says in this week’s portion of Vayakhel (35:27): “And the leaders brought onyx stones and stones for setting into the ephod and breastplate.” The phrase “and the leaders” is usually spelled והנשיאים in Hebrew but the Torah leaves out the two yuds. Why?
Rashi on the verse quoting a Medrish Rabba (Bamidbar Rabba 12:16)comments: “Rebbe Nosson said: ‘Why did the leaders of the tribes see fit to contribute to the dedication of the alter first whereas for building the mishkan (tabernacle) they were not the first to contribute?’ (As soon as the mishkan was erected they immediately contributed the first offerings to be sacrificed on the alter, see Bamidbar [Numbers] 7:1-2) Rather the leaders of the tribes thought as follows: ‘Let the public-at-large contribute, and whatever will be lacking we will supply.’ Once the public supplied all that was needed as it says ‘And the work was sufficient’ (Shemos [Exodus] 36:7), the tribal leaders said ‘What is left for us to do?’ so they brought the onyx stones etc. It is for this reason that they contributed to the altar dedication first. And since, at first, they were somewhat lazy, there is a missing letter, here, from their title.”
The Nachalas Yaakov, a commentary on Rashi, comments that even though the leaders had good intentions to also give merit to all Jews by letting them fulfill the mitzvah of contributing to the building of the mishkan, they were never the less considered lazy because they should have believed that the rest of the Jews would contribute all that was needed for the work. Instead, they were apprehensive and considered that they might not contribute a lot. (Click here for Hebrew text.)
It would seem from here that the leaders of each tribe just wanted to share the wealth and allow others to participate in the mitzvah of contributing to the building of the mishkan. That is why they let the rest of the nation contribute first. But when they saw that there was not much left to contribute accept for the precious stones of the ephod and breastplate, the next time the chance to contribute presented itself, they quickly contributed before anyone else had a chance (to the dedication of the alter).
However there seemed to have been a claim against the leaders for not contributing first towards the building of the mishkan, as we see from their eternal disgraced having the yuds left out of their name in this verse.
Rashi says that the root of their miscalculation was that, deep down, they had feelings of laziness inside them. No matter how miniscule these feelings were, they caused them to not contribute first. But what did they do wrong; they had very pure intentions? They didn’t want to be selfish and hoard the mitzvah, even though they could have contributed everything themselves, or at least most of it. Indeed, they were the leaders, and by doing what they did, they were teaching others how to contribute to the cause!
Ultimately, Hashem, who can gaze deep down into the depths of our hearts and see our entire intentions, no matter how miniscule they may be, sees the source of all reasoning. In this case he saw that their unwillingness to act first did in fact stem from laziness, not from the purest of intentions. For that reason they were disciplined; they then realized their mistake and corrected it at the next possible opportunity, with the dedication of the alter.
It is possible to, at face value, have very fine intentions but, deep down, have it stem from a negative attribute. It is not easy and takes a lot of work, but a person must be in tune with himself and be able to differentiate between the subtleties of motivation, between good and bad. Seeking advice before making a decision can help, but ultimately being in tune with our inner thoughts and psyche, knowing ourselves is the ultimate way, is what helps the most in making the right decision.