Similar concepts also apply with regard to the attribute of fear. It is also an inherent quality, hidden within the heart of every Jew. [For every Jew fears] rebelling against the Holy One, blessed be He, King of kings.

[This quality] must also be brought out from concealment to revelation through meditation. [A person should] contemplate the greatness of the Ein Sof and His sovereignty, that [He is] sovereign over all the worlds, 1 the spiritual and the material. For He fills up all the worlds…. And yet, He ignores all the higher and lower realms and manifests His sovereignty over His nation Israel, and particularly over each individual [Jew]. [For]:

G‑d stands over him, 2 [though] “the entire earth is full of His glory,” 3 He looks at him, and inspects his reins and his heart, [to see] if he is serving Him as is fitting.

Therefore, one must serve Him with awe and fear, as one stands before a king. One should think deeply about this [concept].

Note the concepts in their source, Tanya, ch. 41, and see also ch. 42 which states:

Behold any Jewish person, whoever he may be, when he meditates on the above for a lengthy period each day, [contemplating] how the Holy One, blessed be He, fills the higher realms and the lower realms, the heavens and the earth. And in actual fact, “the entire earth is filled with His glory,”3 and He scans, looks, and checks his reins, his heart, and all of his deeds and speech; and He counts all his steps. This will cause fear to be established within his heart for the entire day, when he will again meditate even with a superficial reflection, 4 at any time, or moment, he will turn away from evil and do good 5 in thought, speech, and deed…

Thus through arousing the fear [of G‑d], the person will be untainted in turning away from evil and doing good, so as not to rebel before the eyes of His glory, heaven forbid, as stated in Tanya, op. cit. Moreover, his involvement in the study of the Torah and the observance of the mitzvos will [possess the advantage of being] the toil of a servant, performed to carry out G‑d’s will, and not for his own satisfaction at all. Instead, [his intent should be] to fulfill G‑d’s will and generate satisfaction for his Creator, as [our Sages said:] 6 “It brings Me satisfaction that I spoke, and My will was done.” The person will also derive pleasure from this, 7 i.e., he will derive pleasure from G‑d’s pleasure. Thus his service will be carried out with happiness as explained in other sources.

{This quality, [Divine service] for the sake of generating satisfaction for G‑d, is also reflected in the love [described with the analogy of a son who exerts himself on behalf of his parents as explained in [Tanya,] chs. 10 and 41. 8 There is, however, a distinction between [the motivations of] love and fear. With regard to love, the individual feels pleasure; he derives personal satisfaction from the unity of the Holy One, blessed be He, and His Shechinah in the lower realms. With regard to fear, by contrast, the person’s service is characterized by a more encompassing bittul. He is not at all concerned with his own satisfaction (for he does not express this dimension of selfhood either). He is satisfied because pleasure is generated in the spiritual realms and this brings him pleasure.

There is a higher rung: that the person feels pleasure because of the fact that the unity of the Holy One, blessed be He, and His Shechinah has been achieved in the lower realms. In this instance, [he feels] the sublime pleasure itself. For the servant is so identified with his Master that he is one entity with Him. Therefore [he feels] the pleasure expressed in the spiritual realms as his own pleasure.}

Thus both love and fear are necessary [for complete Divine service], as explained in Tanya, ch. 41.

Synopsis: [This chapter] explains that every Jew also possesses innate resources of fear [of G‑d]. They must be revealed through meditation. Fear causes a person to be perfect in turning from evil and doing good, and endows his occupation with the Torah and its mitzvos with the advantage of the toil of a servant.