Veyiten Lecha is a Tefillah which is recited on Motzai Shabbos. It is a collection of Pesukim of Brachos from the Tanach.
The opening Pesukim are the brachos which Yitzchak gave to Yaakov in Parshas Toldos. The entire Tefillah is referred to as Veyiten Lecha after its opening words.
There are different Nuschaos of Veyiten Lecha. Some are lengthier, including different types of blessings. Others are more abbreviated.
Early sources and reasons
The practise of reciting Veyiten Lecha on Motzai Shabbos is alluded to in the introduction to the Zohar which teaches;
Those who wait to light the candle on Motzai Shabbos until after the Seder Kedusha (V’ata Kadosh), the wicked in Gehenom accept upon themselves the justice of Hashem and they bring upon him all of the blessings recited by the Tzibbur – Veyiten Lecha and Baruch Atah Ba’ir.
(This is based on the idea that the souls in Gehenom are released over Shabbos and only return after Havdalah. This is one of the reasons that we add the extra Tefillos of Viyi Noam and Veata Kadosh on Motzai Shabbos)
The earliest Halachic source to refer to the custom of reciting Veyiten Lecha on Motzai Shabbos is the Sefer Hamanhig, authored by Rabbi Avraham ben Nosson of Lunil (12th Century). He writes that after we say the Viyhi Noam, which is a Psalm of blessings, we add additional blessings from the 20 verses of Veyiten Lecha.
In his commentary work on the Tefillos, Avudraham, Rabbi David Avudraham (1300s Spain) writes about the custom of saying Veyiten Lecha on Motzai Shabbos. He refers to this Tefillah not as Veyiten Lecha, but as יפתח ה' לך את אוצרו הטוב, which is another Posuk which we recite.
He explains that we recite this prayer because it is filled with Pesukim of blessings and success (ברכה והצלחה) as a good sign for the upcoming week, that our handiwork should be blessed.
Another Rishon who references this custom is the Kol Bo, who writes that after the Chazzan says Havdalah in Shule, he says Veyiten Lecha which are verses of blessing recited as a Siman Tov (good sign). It is also mentioned in Tanya Rabasi and Shibbolei Haleket.
Siddur Beis Avraham explains that Veyiten Lecha is said on Motzai Shabbos because the Zohar teaches that the 6 days of the week receive their blessing from Shabbos. Through saying the Pesukim of blessings, we draw down the blessings from the ‘6 days Above’ (a reference to the Sefiros) into the ‘6 days below’.
Other reasons for the custom is to delay bringing out Shabbos (according to the opinion that Veyiten Lecha is recited before Havdalah). It is also to ensure that no one gets left alone in the Shule because the community finishes davening before them. Further, Veyiten Lecha has Pesukim from Torah, Neviim and Kesuvim and we want to start our week with the merit of Torah.
Yechiel Meir of Gustinin is recorded as saying "I don't know how it is possible for a Jew to have Parnasa during the week without saying the verses of Veyiten Lecha on Motzai Shabbos.
The Mechaber does not mention the reciting of Veyiten Lecha, but it is brought by the Ram"o in the Shulchan Aruch as well as in his work Darkei Moshe.
When to recite it?
There is a Machlokes whether Veyiten Lecha should be recited before Havdalah or afterwards.
Avudraham writes that this is recited after Havdalah in Shule as does the Kol Bo. Other Poskim who rule this way include; Elya Rabbah, Chida and Kaf Hachaim. This was also the preferred practise of the Ariza"l. In the siddur, the Alter Rebbe rules that Veyiten Lecha is said after Havdalah.
One of the reasons for this is that not everyone knew these Pesukim by heart and would need to use candlelight to read them. Preferably, one should not benefit from light on Motzai Shabbos before reciting the blessing of Meorei Haeish in Havdalah and so Havdalah would be recited first.
After noting that the Rishonim write that Veyiten Lecha is said after Havdalah, Pri Megadim writes that the custom is to recite it before Havdalah. The reason is to delay the recital of Havdalah as late as possible so as to maintain the Kedusha of Shabbos. This is also the opinion of the Levush and the Psak of the Mishna Berura.
The custom of the Ariza"l was to recite Veyiten Lecha at home after Havdalah. Some explain that this was following the Sefardi custom of reciting Veyiten Lecha after Havdalah (which he would say at home). However, if the Ariza"l was in the Shule of the Ashkenazim, he would recite Veyiten Lecha in Shule (before Havdalah) so as not to separate from the community.
Chabad custom is to recite Veyiten Lecha after Havdalah. In Sefer Haminhagim it is written that on Motzai Shabbos of Chanukah, the order (at home) is to recite Havdalah, light candles and only then recite Veyiten Lecha.
Other customs
Shaar Hatziyun writes that the custom is to say Veyiten Lecha next to the Havdalah candle, before Havdalah is recited. Siddur Harokeach writes that these Pesukim should be said out loud. It is customary to recite Veyiten Lecha while standing.
Saying with someone else
There is a custom of saying Veyiten Lecha together with another person. The Rebbe explained that this is so we say "May Hashem give to you" to someone else and that we hear "May Hashem give to you" from someone else.
It is recorded that the Rebbe Rashab would say Veyiten Lecha together with his son, the Friediker Rebbe, looking into the same Siddur. The Rebbe said that once in S. Petersburg, the Friediker Rebbe called him to stand next to him and say Veyiten Lecha from the same Siddur. The Rebbe also related that even though the Friediker Rebbe’s time was very precious, he would wait after Havdalah to say Veyiten Lecha with one or more other people while looking in the same Siddur (even though this would take more time).