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Some drink the fourth cup of wine before the piyutim of Nirsah, while others drink the fourth cup after the piyutim of Nirsah.
Piyutim of Nirtzah
- Some have the custom to say Chasal Siddur Pesach after the 4th cup of wine and some say it after Chad Gad Yah. Others don't say Chasal Siddur Pesach at all. 
- It is customary to say LeShanah HaBah BeYerushalayim. Some say it once, while others say it three times. Some say it after the piyut Ki Lo Naeh. 
- Some say Az Rov Nissim the first night and Ometz Gevurtecha the second night. Some say both piyutim on both nights and some say Az Rov Nissim the first night and both the second. 
- It is customary to say Chad Gad Yah in Nirtzah. 
- Some have the custom to say Shir HaShirim after the Seder. 
- It is customary to sing Echad Mi Yodeh and some do so in the vernacular. 
Going to sleep after the Seder
- According to Sephardim, before going to sleep, one should say the full Kriyat Shema with 3 paragraphs. If it before Chatzot, one should say the Bracha of HaMapil with Shem UMalchut, and if it's after Chatzot one should say this bracha without Shem UMalchut. 
- Nitei Gavriel (Pesach v. 2, p. 569). See Mishna Brurah 480:6
- Nitei Gavriel (Pesach v. 2, p. 568)
- Nitei Gavriel (Pesach v. 2, p. 569)
- Nitei Gavriel (Pesach v. 2, p. 569), See Kaf HaChaim 480:11
- Chazon Ovadyah (vol 2, pg 126) quotes Chaim Shaal who records a story of a person who joked about Chad Gad Yah and was put in cherem until he asked for forgiveness.
- Chida in Moreh Etzbah 7:210, Kaf HaChaim 480:12, Chazon Ovadyah (vol 2, pg 126)
- Nitei Gavriel (Pesach v. 2, p. 570)
- Chazon Ovadyah (vol 2, pg 126)