Parashas Masei · Passuk 35:20 · TT note 2
Chabad.org — English translation + Rashi
Torah Temimah points to Sifrei (TT note on “בִּצְדִיָּה”).
English: “Or throws something upon him with intent” — “with intent” means that he laid in wait for him and intended [to kill] him.
Definition of intentional ambush (tzediyah) as a capital act.
Throwing an object that kills only incurs capital liability when the thrower deliberately ambushed and aimed at the victim.