Hebrew, then English. Open "What it means" under any line for the explanation.
Tehillim (Psalm) 90. The seventh of the ten psalms of the Tikkun HaKlali:
תְּפִלָּה לְמֹשֶׁה אִישׁ הָאֱלֹהִים אֲדֹנָי מָעוֹן אַתָּה הָיִיתָ לָּנוּ בְּדֹר וָדֹר.
A prayer of Moshe, the man of God. My Master, You have been a home for us in every generation.
What it means
Rashi (the main medieval commentator, France, 1000s): Moshe said this psalm and the ten after it, up to Tehillim 100. They match the eleven blessings he gave the tribes before he died. The Midrash (the rabbis' teaching on Tehillim) says Shimon is the tribe he did not bless.
Rashi on Tehillim 90:1; Midrash Tehillim 90:1בְּטֶרֶם הָרִים יֻלָּדוּ וַתְּחוֹלֵל אֶרֶץ וְתֵבֵל וּמֵעוֹלָם עַד עוֹלָם אַתָּה אֵל.
Before the mountains were born, before You brought forth the earth and the world, from forever to forever You are God.
What it means
Why mountains? Ibn Ezra (a Spanish commentator who died in the 1160s) says they are the things that stand as if they had always been there. The psalm says there was a time before even they existed.
Ibn Ezra on Tehillim 90:2תָּשֵׁב אֱנוֹשׁ עַד דַּכָּא וַתֹּאמֶר שׁוּבוּ בְנֵי אָדָם.
You bring a human back until he is crushed, and You say, "Return," children of Adam.
What it means
The Gemara (the rabbis' discussions built on the Mishnah) reads this as proof that teshuvah, returning to God, was created before the world. Ibn Ezra reads "return" plainly: back to the dust people were taken from.
Pesachim 54a; Ibn Ezra on Tehillim 90:3כִּי אֶלֶף שָׁנִים בְּעֵינֶיךָ כְּיוֹם אֶתְמוֹל כִּי יַעֲבֹר וְאַשְׁמוּרָה בַלָּיְלָה.
For a thousand years in Your eyes are like yesterday when it has passed, or a watch in the night.
What it means
Rashi counts God's day as a bit less than a thousand years. God told Adam, the first man, that he would die "on the day" he ate from the tree. Adam lived 930 years, so he died inside one of God's days.
Rashi on Tehillim 90:4; Bereishit 2:17 and 5:5זְרַמְתָּם שֵׁנָה יִהְיוּ בַּבֹּקֶר כֶּחָצִיר יַחֲלֹף.
You sweep them away. They become sleep. In the morning, like grass that renews itself.
What it means
You sweep them away. They become sleep. In the morning they are like grass that renews itself.
Radak (Rabbi David Kimchi, Provence, around 1200) hears "sleep" as a dream. When you wake up, nothing from the dream is left.
Radak on Tehillim 90:5בַּבֹּקֶר יָצִיץ וְחָלָף לָעֶרֶב יְמוֹלֵל וְיָבֵשׁ.
In the morning it blooms and renews. Toward evening it wilts and dries out.
What it means
In the morning it blooms and renews itself. Toward evening it wilts and dries out.
Ibn Ezra sees two pictures. One generation blooms and the next replaces it: he reads chalaf as the word for a change, as in a change of clothes. And one human life is like one day, from morning to evening.
Ibn Ezra on Tehillim 90:6כִּי כָלִינוּ בְאַפֶּךָ וּבַחֲמָתְךָ נִבְהָלְנוּ.
For we are finished by Your anger, and by Your fury we are terrified.
What it means
Radak hears a change here. Until now the psalm spoke about all people. From here it speaks in the voice of the Jewish people in exile: even people at ease pass quickly, so how much more we do.
Radak on Tehillim 90:7שַׁתָּ עֲוֺנֹתֵינוּ לְנֶגְדֶּךָ עֲלֻמֵנוּ לִמְאוֹר פָּנֶיךָ.
You have put our wrongs in front of You, our hidden things in the light of Your face.
What it means
Two readings of "alumenu." Rashi: the wrongs of our youth. Ibn Ezra and Radak: things that are hidden. Nothing is hidden in the light of Your face.
Rashi, Ibn Ezra and Radak on Tehillim 90:8כִּי כָל יָמֵינוּ פָּנוּ בְעֶבְרָתֶךָ כִּלִּינוּ שָׁנֵינוּ כְמוֹ הֶגֶה.
For all our days turn away in Your wrath. We finish our years like a murmur.
What it means
Ibn Ezra on hegeh: speech does not stay. The moment someone says a word it exists, and right after it is as if it never was. That is what he says our years are like.
Ibn Ezra on Tehillim 90:9יְמֵי שְׁנוֹתֵינוּ בָהֶם שִׁבְעִים שָׁנָה וְאִם בִּגְבוּרֹת שְׁמוֹנִים שָׁנָה וְרָהְבָּם עָמָל וָאָוֶן כִּי גָז חִישׁ וַנָּעֻפָה.
The days of our years come to seventy years, and if with strength, eighty years. Their best part is toil and trouble, for it is cut off quickly and we fly away.
מִי יוֹדֵעַ עֹז אַפֶּךָ וּכְיִרְאָתְךָ עֶבְרָתֶךָ.
Who knows the force of Your anger? And as the awe of You, so is Your wrath.
What it means
Who knows the force of Your anger? As great as the awe of You, so is Your wrath.
A hard verse. Radak: the more a person is in awe of God, the more even a small mistake counts. His example is Aharon's two sons, who died after bringing an offering God had not asked for: "Through those close to Me I am made holy."
Radak on Tehillim 90:11; Vayikra 10:1-3לִמְנוֹת יָמֵינוּ כֵּן הוֹדַע וְנָבִא לְבַב חָכְמָה.
To count our days in this way, teach us, and we will bring a heart of wisdom.
What it means
The Midrash on this verse: if we knew when we would die, we would do teshuvah.
Midrash Tehillim 90:9שׁוּבָה יְיָ עַד מָתָי וְהִנָּחֵם עַל עֲבָדֶיךָ.
Come back, Hashem. How long? And relent about Your servants.
What it means
Can God change His mind? Ibn Ezra says "relent" is a figure of speech, taken from how a person behaves. Moshe used these same two verbs, "turn back" and "relent," when he prayed after the people made the golden calf.
Ibn Ezra on Tehillim 90:13; Shemot 32:12שַׂבְּעֵנוּ בַבֹּקֶר חַסְדֶּךָ וּנְרַנְּנָה וְנִשְׂמְחָה בְּכָל יָמֵינוּ.
Satisfy us in the morning with Your kindness, and we will sing out and rejoice all our days.
What it means
What is the morning? Rashi: the day of rescue, the morning after the night of trouble. Ibn Ezra: our youth. If You teach us the right path when we are young, we will be happy even in old age.
Rashi and Ibn Ezra on Tehillim 90:14שַׂמְּחֵנוּ כִּימוֹת עִנִּיתָנוּ שְׁנוֹת רָאִינוּ רָעָה.
Make us happy for as many days as You afflicted us, for as many years as we saw trouble.
What it means
Rashi: make us happy in the days of the Mashiach (the promised king who will bring the final redemption) for as many days as You made us suffer in exile. Radak does not read it as a count of days, as the Midrash does. He reads: as You made us suffer, so make us happy forever.
Rashi and Radak on Tehillim 90:15יֵרָאֶה אֶל עֲבָדֶיךָ פָעֳלֶךָ וַהֲדָרְךָ עַל בְּנֵיהֶם.
Let it be seen by Your servants, Your work, and Your splendor on their children.
What it means
Radak: the parents ask that the rescue meant for their children's days come in their own, so that parents and children are there for it together.
Radak on Tehillim 90:16וִיהִי נֹעַם אֲדֹנָי אֱלֹהֵינוּ עָלֵינוּ וּמַעֲשֵׂה יָדֵינוּ כּוֹנְנָה עָלֵינוּ
May the pleasantness of my Master, our God, be upon us, and the work of our hands establish for us.
What it means
Rashi: noam is God's presence and His comfort. This verse is also the opening of Vihi Noam, said on Saturday night. That prayer tells why.
Rashi on Tehillim 90:17וּמַעֲשֵׂה יָדֵינוּ כּוֹנְנֵהוּ.
And the work of our hands, establish it.
What it means
Ibn Ezra: the first request is to fix whatever would make the work exhausting. The second, "establish it," is that it come out complete, as in "Unless Hashem builds the house" (Tehillim 127:1).
Ibn Ezra on Tehillim 90:17