Shemot ( Exodus ) 23.25
You shall worship Hashem, your G-d, and He shall Bless your bread and your water, and I shall remove illness from your midst:
By this injunction we are commanded to serve G-d. This command imposes the specific duty of Prayer. The Sifre says: to serve Him means Prayer. The Sages also say: to serve Him means study of the Law.
(sifre means book in Aramaic – so there is a sifre on the book of Bamidbar (Numbers) and on the book of Devarim( Deuteronomy), etc….
Devarim (Deuteronomy) 13.5
אַחֲרֵי יְהֹוָה אֱלֹהֵיכֶם תֵּלֵכוּ וְאֹתוֹ תִירָאוּ וְאֶת מִצְוֹתָיו תִּשְׁמֹרוּ וּבְקֹלוֹ תִשְׁמָעוּ וְאֹתוֹ תַעֲבֹדוּ וּבוֹ תִדְבָּקוּן
You shall walk after the L-rd your G-d, and fear Him, and keep His Commandments, and obey His Voice, and you shall serve Him, and hold fast to Him:
Devarim (Deuteronomy) 6.13
אֶת יְהֹוָה אֱלֹהֶיךָ תִּירָא וְאֹתוֹ תַעֲבֹד וּבִשְׁמוֹ תִּשָּׁבֵעַ
You shall fear the L-rd your G-d, and serve Him, and shall swear by His Name:
Devarim (Deuteronomy) 11.13
וְהָיָה אִם שָׁמֹעַ תִּשְׁמְעוּ אֶל מִצְוֹתַי אֲשֶׁר אָנֹכִי מְצַוֶּה אֶתְכֶם הַיּוֹם לְאַהֲבָה אֶת יְהֹוָה אֱלֹהֵיכֶם וּלְעָבְדוֹ בְּכָל לְבַבְכֶם וּבְכָל נַפְשְׁכֶם:
And it shall come to pass, if you shall give heed diligently to My commandments which I command you this day, to love the L-rd your G-d, and to serve him with all your heart and with all your soul (nefesh).
Maimodes states in Guide For The Perplexed page 385 Man’s love of G-d is identical with his knowledge of Him. The Divine service enjoined in these words must, accordingly, be preceded by the love of G-d. Our Sages have pointed out to us that it is a service in the heart, which explanation I understand to mean this: man concentrates all his thoughts on the First Intellect, and is absorbed in these thoughts as much as possible.
Rambam states in the Yad hachzakah:, Laws Concerning the Fundamentals of our Faith, ch.1 Law 11, and He does not change, for there is nothing that can cause change in Him. There does not exist in Him… anger or laughter, happiness or sadness… G-d is not improved, happier, in a better state of being if we serve Him or in a worse state if we do not serve Him. Our G-d is awesome and we cannot affect Him in any way whatever. Whether we are evil or righteous, religious or atheistic, G-d remains unaffected. He, the Supreme Being, is not in need of anything including our worship of Him. Why then do we worship G-d? Because in so doing we fulfill the Divine potential G-d has endowed us with. The worship of G-d through Torah study brings into realization the highest element in our nature and gives us true existence and fulfillment.
The ability to pray is identified by the sages as a power of the heart: What is the toil of the heart? Prayer? Prayer depends on the sensitivity and delicate nature of the heart, which can only be refined by truly connecting to and internalizing the lessons gathered from one’s study of the Torah. A Heart of Knowledge refers to the heart’s ability to grow into a sanguine and fully developed center for one’s sensitivity to feelings.
Psalm 34.16 The eyes of the L-rd are to the righteous, and His ears are to their cry.
עֵינֵי יְהֹוָה אֶל צַדִּיקִים וְאָזְנָיו אֶל שַׁוְעָתָם
The eyes [einei] of G-d are to the righteous [tzadikim]. To each potential tzadik G-d Gives His Eyes, His Ability to look into the Torah (the secret of the insight of His right eye) and His Ability to thereby create (and rectify) reality (the secret of the power of His left eye). http://www.inner.org/hebrew_calendar/tu-bishevat/tree-of-life.php
Divrei Hayamim 1 ( 1 Chronicles ) 28.9
אָבִ֜יךָ לֹהֵ֨יאֶ־תאֱ דַּע֩ שְׁלֹמֹֽה־בְנִ֡י וְאַתָּ֣ה
כָל־לְבָבוֹת֙ כִּ֚י חֲפֵצָ֔ה וּבְנֶ֣פֶשׁ שָׁלֵם֙ בְּלֵ֚ב וְעָֽבְדֵ֗הוּ
מֵבִ֑ין מַֽחֲשָׁב֖וֹת רוְכָל־יֵ֥צֶ יְהֹוָ֔ה דּוֹרֵ֣שׁ
יַזְנִֽיחֲךָ֥ וְאִם־תַּֽעַזְבֶ֖נּוּ לָ֔ךְ איִמָּ֣צֵ אִֽם־תִּדְרְשֶׁ֙נּוּ֙
And you, my son Solomon, know the G-d of your father and worship Him with a whole heart and with an eager soul, for the L-rd Seeks all hearts, and He Understands the thoughts of every creation; if you seek Him, He Will be found to you, and if you forsake Him, He Will abandon you forever.
If you seek Him, He Will be found to you: Therefore, I say, ( verse 8 ) and seek all the Commandments of the L-rd
Divrei Hayamim 1 ( 1 Chronicles ) 28:8
And now, before the eyes of all Israel, the congregation of the L-rd, and in the ears of our G=d, … observe and seek all the commandments of the L-rd your G-d in order that you inherit the good land and bequeath it to your sons after you forever.
עִבְדוּ אֶת יְהֹוָה בְּיִרְאָה וְגִילוּ בִּרְעָדָה
נַשְּׁקוּ בַר פֶּן יֶאֱנַף וְתֹאבְדוּ דֶרֶךְ כִּי יִבְעַר כִּמְעַט אַפּוֹ אַשְׁרֵי כָּל חוֹסֵי בוֹ:
Serve the L-rd with fear, and rejoice with trembling:
Worship in purity, lest He be Angry, and you perish from the way, for in a little while His Wrath will blaze;
Happy are all who put their trust in Him: Tehilim Psalm) 2.11-12
This prayer is from the Siddur for Shachrit.
רֵאשִׁית חָכְמָה יִרְאַת יְהֹוָה שֵׂכֶל טוֹב לְכָל עֹשֵׂיהֶם תְּהִלָּתוֹ עֹמֶדֶת לָעַד.
The fear of the L-rd is the beginning of wisdom; a good understanding have all those who do His Commandments; His Praise Endures forever.
The beginning of wisdom is the fear of the L-rd, and the knowledge of the holy ones is understanding. Mishlei (Proverbs) 9.10
So to conclude – to worship G-d means to serve Him, to pray, praise Him and to study His Mitzvot and keep them.
May we try each day to learn about G-d, to follow His Ways and His Truth
Blessings and Peace