וּסְפַרְתֶּ֤ם לָכֶם֙ מִמָּחֳרַ֣ת הַשַּׁבָּ֔ת מִיּוֹם֙ הֲבִ֣יאֲכֶ֔ם אֶת־עֹ֖מֶר הַתְּנוּפָ֑ה שֶׁ֥בַע שַׁבָּת֖וֹת תְּמִימֹ֥ת תִּהְיֶֽינָה׃
<span class="x" onmousemove="Show('perush','Este es el <b>161er Precepto Positivo</b> enumerado por el Rambam en el Prefacio a Mishné Torá, su “Compendio de la Ley Hebrea” para todo el Pueblo de Israel.',event);" onmouseout="Close();">Y os habéis de contar desde el siguiente día del sábado</span>, desde el día en que ofrecisteis el omer de la ofrenda mecida; siete semanas cumplidas serán:
Kitzur Shulchan Arukh
It is the custom that no work is performed, by either men or women during the Sefirah days, from sunset, until after the counting of the Omer. There is an allusion for this (in the Torah), because it is said, "Seven weeks" (Leviticus 23:15). [The word shabbasos, meaning weeks,] is derived from shevos, denoting rest, indicating that during the time we count the Omer, that is from sunset on, you should rest [refrain] from doing any work, until after you have counted the Omer.
Kitzur Shulchan Arukh
On the first night of Shavuos, the Maariv service is delayed, until the stars come out, for, if we would hold the service before this time, and usher in the Yom Tov, a bit of time will be lacking from the forty-nine days of the Sefirah, and the Torah says, "They shall be seven complete weeks" (Leviticus 23:15).
Mishneh Torah, Positive Mitzvot
To count forty-nine days from the time of cutting the Omer (first sheaves of the Barley Harvest), as it is said, “And ye shall count unto you from the morrow after the Sabbath (feast)” (Lev. 23:15).