Rashi on Numbers 24:21/רש"י על במדבר כ״ד:כ״א

1וירא את הקיני AND HE SAW THE KENITES — Because the Kenites were settled near the Amalekites — just as it is stated, (I Samuel 15:6) “And Saul said unto the Kenites, [Go, depart, get you down from among the Amalekites]’’ — he mentioned them immediately after the Amalekites. He beheld the greatness of the descendants of Jethro, of whom it is said, (I Chronicles 2:55) “The תרעתים, שמעתים, שוכתים" — [These are the Kenites] (see Sifrei Bamidbar 78:1 on Numbers 10:29; Sanhedrin 104a, 106a, Sotah 11a).

2איתן מושבך FIRM IS THY DWELLING PLACE — “I wonder whence you merited this; for were you not with me in the advice we gave Pharaoh (Exodus 1:10): ‘Come, let us deal wisely with them’, and now you have a seat in the strength and power of Israel, (in the Sanhedrin)’’! (Sanhedrin 106a).