The month of Elul is commonly known as the month of “rachamim and selichot”, mercy and forgiveness.
“From Rosh Hodesh Elul until after Yom Kippur is a time of (Divine) favor. Although, throughout the entire year, the Holy One, blessed be He, accepts the repentance of those who return to Him wholeheartedly, in any case, these days (between the 1st of Elul and Yom Kippur) are more special and have been set aside for repentance, because they are days of mercy and favor.”
The theme of rachamim is very prevalent in our tefilah the whole year round; however from the beginning of Elul through to Yom Kippur it becomes almost predominant in all the additions and special tefilot for these days. The thirteen attributes of rachamim form the backbone of our selichot and we find ourselves constantly beseeching Hashem to relate to and judge us with mercy, rachamim.
However, it would seem that rachamim is not suitable when we are expected to be involved in the process of doing teshuva, repentance. When doing teshuva we are expected to be fully aware of what we have done, regret it and accept upon ourselves never to return to those things for which we are repenting. Teshuva is first and foremost admitting responsibility. Rachamim on the other hand seems to be a request for ungrounded, gratuitous forgiveness. How do these two concepts come together at a time when we are supposed to be committed to answerability for our actions?
Furthermore, in this week’s Parsha, Ki Tetze, apparently we find an adverse attitude of Chazal towards employing the attribute of mercy in our tefilah. The Mishnah states that one who says in their prayer “Hashem, have mercy upon us just like You have mercy on the bird’s nest” (a reference to the Mitzvah of Shiluach Haken, the sending away of the mother bird before taking the baby birds or eggs) must be silenced. This type of speech in tefilah is forbidden and must be stopped immediately.
The gemara proceeds to ask why such a thing is prohibited and one of the answers given is: “because he makes God’s attributes mercy, and they are but decrees.” Many different explanations have been given for this gemara and it also became the basis of a big argument between the Rambam and Ramban regarding Ta’amei Mitzvot, reasons for the Mitzvot, however, in the context of our discussion regarding the attribute of mercy and it’s place in tefilah I would like to share with you the comments of Rav Kook on this gemara.
Usually we understand the concept of rachamim as being an act of kindness towards someone who is undeserving of it. However, Chazal always contrast rachamim against din, judgment. Din depicts the notion of looking at something for what it is at present, no more and no less. The gemara states that a judge can only rule based on what his eyes see. He cannot speculate about things which are not apparent or certain or might happen in the future.
Rachamim on the other hand, explains Rav Shimshon Rephael Hirsch, comes from the word “rechem” – womb.
Rachamim, the feeling that we are to have inherited, means more than pity. The word is derived from ‘rechem’ by which is designated the most self-sacrificing energy of one being for the formation of another being to come into existence and be completed. ‘Rechem’, the womb, is the hearth of the deepest devotion. 
The womb is the place where new life starts and is nurtured for its fantastic future. The womb epitomizes the concept of nurturing something small and preparing it for its eventual full potential.
When we employ the attribute of mercy in our tefilah, it is not a request for ungrounded, undeserving compassion, rather it is to awaken in ourselves the awareness that despite what we have done, and despite our shortcomings, we must be conscious of the ability for us to make amends and continue to progress and realize our full potential. The core theme of teshuva is to always strive to continue to progress to the next level of who we can become and not remain stagnant in the place that we were a year, month, day or even a moment ago. Teshuva and rachamim go hand in hand in our attempt to cause the shechina to move from the “chair” of din and judge us from the “chair” of rachamim.
The reason why Chazal in the Mishna forbid one to evoke the attribute of rachamim in tefilah is because if one recognizes rachamim only expressed in the pity Hashem has for the mother bird, it means that one has reduced rachamim to its distorted meaning of “rachmones” – baseless compassion. The truth, says Rav Kook, is that rachamim, the true understanding of it, ie: the eternal evolvement of life and reality to its full potential, permeates our whole existence and is to be found everywhere.