What is the connection between the current Parshah and the previous one?
Seforno: After discussing Mitzvos in connection with settlement of the land, the Torah presents Mitzvos that concern the settling of the Shechinah in the land - warnings how to avoid causing It to be withdrawn - via defective offspring, forbidden relations, the mixing of Pasul women and Tum'ah in the camp.
Rosh: Since the Torah juxtaposes "Ki Yikach Ish Ishah" to the Mitzvah of Tzitzis, it is customary to purchase a Talis for a Chasan when he marries. 1
Hadar Zekenim (in Pasuk 12) It is the source of the custom to spread a Talis over the Chasan and Kalah during the Chupah, to inaugurate them in Mitzvos.
Oznayim la'Torah: Because Tzitzis is Segulah (an antidote) against Z'nus - as the Torah writes in Sh'lach-l'cha, Bamidbar, 15:38 "u'Re'isem oso ... ve'Lo Sasuru Acharei Levavchem ve'Acharei Eineichem". 2
Why does the Torah add the word "u'Sene'ah"?
Rashi: To teach us that 'Aveirah Goreres Aveirah' (One sin leads to another). 1 Once he transgresses the sin of "Lo Sisna es Achicha ... ", he will go on to transgress the sin of speaking Lashon ha'Ra.
Sifri: 'See what a terrible thing is hatred - the man transgressed " Ve'ahavta le'Re'acha Kamocha, then "Lo Sisna", then "Lo Sisna es Achicha" until he finally commits murder. 2
