Parashas Haazinu · Passuk 32:2
Torah Temima points to the derasha of Rabbi Bena’ah on Torah study lishmah and shelo lishmah.
English: It was taught: Rabbi Bena’ah would say, Anyone who occupies himself with Torah not for its own sake, it becomes for him a deadly poison, as it is said “My teaching shall drop as the rain” … and “arifah” means killing.
A dual reading of the rain metaphor according to the intention of the student.
Just as rain can bring life when it falls in its proper time and death when it falls out of season, so Torah studied lishmah is a potion of life and Torah studied shelo lishmah becomes a potion of death. The same verse yields both outcomes according to the learner’s purpose.