The Rabbis teach that the sanctity of Shabbat day exceeds that of Shabbat evening. This is mentioned in a number of works, including the Or Ha'hayim (by Rav Haim Ben Atar, Morocco-Israel, 1696-1743) and the Shulhan Aruch. The Friday night meal corresponds to Yishak Abinu, whereas the Shabbat morning meal corresponds to Abraham Abinu, thus signifying a higher level of Kedusha (sanctity). Furthermore, in Kabbalistic thought the night of Shabbat represents the "female" aspect of Shabbat, the quality of receiving and accepting, whereas Shabbat day symbolizes the "male" quality of giving and impacting.
For this reason, during the Arbit service on the night of Shabbat we recite, "Ve'yanuhu Bah Yisrael" ("Israel shall rejoice on it"), employing the feminine form, "Bah." On Shabbat morning, however, we recite "Ve'yanuhu Bo Yisrael," using the masculine form, "Bo."
There is a debate among the authorities concerning the proper text to recite in the corresponding passage in the Shabbat Minha service. The Shiyureh Keneset Ha'gedola (Rav Haim Banbenishti of Turkey, 1603-1673), in Siman 265, writes (listen to audio recording for precise citation) that the practice is to employ the plural form during Minha – "Ve'yanuhu Bam." On Shabbat night, Shabbat is compared to a bride, on Shabbat morning it is likened to a groom, and on Shabbat afternoon it resembles the union between the bride and groom. Hence, during the Shabbat Minha service we refer to Shabbat with the plural form, "Ve'yanuhu Bam." This is also the position of the Hida (Rav Haim Yosef David Azulai, 1724-1806), in his work Mahazik Beracha.
By contrast, Rav Shalom Moshe Hai Gagin, in his work Yismah Leb, cites from the Rashash (Rav Shalom Sherabi, Yemen-Israel, 1720-1777) that the proper text even during Minha is "Ve'yanuhu Bo." In fact, it is recorded that the Rashash was explicitly asked this question and responded, "Misva Bo" – the correct text is "Bo," rather than "Bam." Likewise, Rav Abraham Antebbe (1765-1858), in his work Hochma U'musar, states plainly that on Shabbat day we recite the text, "Ve'yanuhu Bo," drawing no distinction between Shaharit and Minha. This would clearly indicate that this text is used during both prayer services. And the Ben Ish Hai (Parashat Vayera) records that the practice among the Kabbalists of Yeshivat Bet El was to recite "Bo."
It is worth mentioning that, as the Ben Ish Hai notes in other context, that the Hida was unaware of the Rashash's rulings, and had he seen the Rashash's works, he presumably would have accepted his views. And when it comes to liturgical texts, the Rashash meticulously followed the rulings of the Arizal (Rabbi Yishak Luria of Safed, 1534-1572). Hence, it would seem that the text of "Bo" is the more authoritative version, which even the Hida would have accepted had he been aware of the Rashash's rulings.
Accordingly, Hacham Ovadia Yosef rules (in Hazon Ovadia, p. 346; listen to audio recording for precise citation) that it is preferable to recite "Ve'yanuhu Bo" during the Shabbat Minha service, rather than "Ve'yanuhu Bam." Nevertheless, he adds, those who recite "Bam" certainly have authorities on whom to rely, and they may therefore continue this practice. Hacham Ovadia notes, however, that one who chooses to recite "Bam" must be grammatically consistent, and change the word "Shabbat" in the preceding clause ("Be'ahaba U'be'rason Shabbat Kodshecha") to the plural term, "Shabbatot." Since he employs the plural term, "Bam," he must similarly refer to Shabbat with the plural "Shabbatot."
Summary: Different views exist as to whether in the Shabbat Minha service one should recite the text, "Va'yanuhu Bo Yisrael," as we do on Shabbat morning, or "Va'yanuhu Bam." Both practices are acceptable, though the version of "Bo" seems to be the more authoritative text. One who recites "Va'yanuhu Bam" must ensure to recite "Shabbatot" instead of "Shabbat" in the preceding clause.
