And the Torah didn’t mention the Temple and the smell of the scent of the sacrifices, when it mentioned here that there was no fire coming down and consuming the sacrifices in the Second Temple. (Ramban on Vayikra 26:16)

There are situations in which we can elect to do a mitzvah, but we are not obligated to do so. The Chasam Sofer and the Steipler both tell us that this is the ultimate litmus test to determine our love for Hakadosh Baruch Hu. When we do a mitzvah that is mandatory, it may be out of fear of retribution, however if we are not commanded but do it anyway, we show that our true desire is to serve Hashem. This concept is amplified in the gemora in Menachos, which tells us that though Hashem does not require that a person wear a four-cornered garment (which would be obligated in tzitzis), if he doesn’t wear such a garment, then Hashem has an unfavorable disposition towards this person, and he may be punished for not seeking to do the mitzvah.

I would like to explain this with a mashal. Imagine a child who every morning prepares a coffee for his father. He was never asked but did it as an expression of love and admiration. One morning the father tells the son, “Please bring me a book from the basement.” After a few minutes the father comes to the kitchen to find his son busy doing something else – there is neither a book nor coffee! If there had been a book but no coffee, that would have been what the father expected. If there had been a coffee but no book, that would also have been excusable. But no book and no coffee is a clear message to the father that today the son is really not interested in pleasing him at all.

Similarly, when Hashem is upset with a person for infractions which he did, then the fact that he didn’t voluntarily wear tzitzis will add fuel to the fire.

There is another concept which shows the opposite, in that there are situations when one should refrain from performing a mitzva. The mitzvah of tzedakah is applauded by Chazal and is given an unbelievable significance in our religious observance, to the point that we learn from a verse that even prayer should be prefaced with the giving of tzedakah. Yet, Rav Yaakov Emden and others make it clear that before maariv one should not give tzedakah: Our relationship with Hashem is one of Midas Hadin at night, and it is inappropriate to give tzedakah when one is in a relationship of Midas Hadin. Though tzedakah is an important mitzvah, it must be done at the right time, and if done at the wrong time it could show a callousness in understanding our connection to Hashem. (Of course, one should give Tzedaka to a poor person even at night!)

Harav Tzvi Pesach Frank, the Rav of Yerushalayim, points to the Ramban in this week’s parsha that tells us that Hashem was displeased with Klal Yisrael at the time of the second Beis Hamikdash and He did not fully accept the sacrifices that were offered on the altar. With this Rav Frank explains the position of the Rambam who states that even when the Beis Hamikdash is not there, certain sacrifices can still be brought. He questions, “Why is it that the tzadikim and gaonim from the times of the Mishna and onwards did not bring offerings if they were permitted?” He answers, “It is not a question of permissible or forbidden, rather this is the question:  Is now the right time to be doing this act? Going up to the Har Habayis or bringing a korban is an act that brings one closer to Hashem, but only when our present relationship with Hashem suggests and warrants it. “

Before we do mitzvos, there are those who have the custom of saying a small prayer that our service should be accepted by Hashem.

As we count Sefira towards Shavuos, we are not only preparing ourselves to accept the Torah, but we are also creating an atmosphere in which our actions will be desirable and accepted by Hashem.