What is the meaning of "Lo Sochlu Al ha'Dam"?
Rashi #1 (from Sanhedrin 63a) 1 and Targum Yonasan: It is a prohibition against eating the meat of Kodshim before the blood has been sprinkled.
Rashi #2 from Sanhedrin 63a): Do not eat from the flesh of an animal whilst it is still alive.
Moshav Zekenim, citing Sanhedrin 63a: We are not Mavreh (serve to mourners the first meal after the burial) for people that Beis Din executes. 4
Sanhedrin 63a: Beis Din may not eat on the day they kill someone.
Sanhedrin 63a: This is the warning not to become a Ben Sorer u'Moreh.
Brachos 10b: Do not eat before 'praying for your blood' (each day, starting from the morning). Moshav Zekenim - one must bless 49 Brachos (the Gematriya of "ha'Dam") before eating [bread] - 47 in Shacharis 5 , Al Netilas Yadayim and ha'Motzi.
Moshav Zekenim #1: Do not eat without washing your hands. The Gematriya of "Al ha'Dam" equals that of "Zeh b'Lo Netilah."
Moshav Zekenim #2: Do not eat without Talmud Torah, which is expounded in 49 (the Gematriya of "ha'Dam") reasons for Taharah, and 49 for Tum'ah. 6
Moshav Zekenim (from Shabbos 41a): Do eat without drinking. One who does so, his eating is [like spilling his own] blood. Danger is more stringent than Isur!
See Peirush Yonasan and Na'ar Yonasan.
Ramban, Moshav Zekenim: This is like the other Lavin in the Pasuk. And it entailed gathering blood into a pit, thereby attracting the demons, whom they would then question about the future - and that was the sin of King Sha'ul's army (Shmuel 1, 14:32,33)., who were terrified of the P'lishtim, whom they were currently fighting. Rashbam - it entailed eating by the grave and performing witchcraft to prevent the deceased from taking revenge, or some other kind of witchcraft.
Seforno: which the Torah forbids because it means departing from the Ru'ach Taharah that surrounds Yisrael to a Ru'ach Tum'ah.
Moshav Zekenim: The Gemara says the same about people killed by the kingdom. In any case there is Aveilus over such people.
This includes Birkos ha'Shachar, on Talis, Tefilin, Pesukei d'Zimra and Keri'as Shma, and Shemoneh Esre. On Shabbos morning there is no Brachah on Tefilin, but there is Kidush. (PF)
What is Nichush ?
Rashi: It is superstition - If one comes across a weasel or a bird; 'The bread fell from his mouth!' 'A deer crossed his path!' 1
Ramban (in Devarim 18:9): It is trying to know the future via the chirping of birds or looking at their wings.
Moshav Zekenim citing the Rosh: It is testing (to understand hidden matters) through forms, sticks, actions and movements - "Nichashti va'Yvarcheni Hashem Biglalecha" (Bereishis 30:27).
Targum Yonason: One may not follow it [even if others concocted the Nichush - Yayin ha'Tov]. See Na'ar Yonasan.
What is "Lo Se'onenu"?
Rashi: It is superstition connected to times - 'Such and such a day is good to start working!', That time of day is bad to go out!' 1
Ibn Ezra, Moshav Zekenim, Ramban (Devarim 18:9): It is trying to know the future via the formation of the clouds.
Targum Yonasan: It is deceptive (sleight of hand) magic. 2
Moshav Zekenim citing the Rosh: It is permitted if there is a proper reason to say so.
So he wrote in Devarim 18:10. Also here, the text said 'Charurei Einin', and there was a reference to Sanhedrin 65b, and a printer erred and copied 'Achurei Sanhedrin Einin' (PF, based on Yayin ha'Tov). The Na'ar Yonasan however, accepts the latter version, which he explains to mean that one should not take one's cue from the Sanhedrin, who were conversant with all forms of sorcery
Why is "Lo Sochlu Al ha'Dam" written next to Orlah?
Moshav Zekenim citing the Rosh: Just like one must wait before eating Peros of a new tree, one must wait for an animal to die before eating from it.