Rett kindly gave reference to Maharahulovada sutta.
Sangiti sutta, where tejo-kasina is mentioned, is Digha Nikaya 33.
It's interesting that Visuddhimagga (chapter V) gives reference to the
case you analyze:
"The fire kasina is the basis for such powers as smoking, flaming,
causing showers of sparks, countering fire with fire, ability to burn
only what one wants to burn (S.iv,290), causing light for the purpose of
seeing visible objects with the divine eye, burning up the body by means
of the fire element at the time of attaining nibbana (MA.iv,196)."
The tejo-kasina is mentioned in various parts of Sutta-pitaka about 10
times.