can judges add the word rigorous when they award life imprisonment?

Accused named, Ram Kumar Sivare has been convicted by lower court in a murder case and hence,  award of rigorous life imprisonment given to him by the court. This was confirmed by Chattisgarh HC.
Senior advocate Parmanand Katara, appearing for the accused approach Supreme Court, he contended that the judgement pronounced by the courts below was “unconstitutional and ultra-vires” as penal and procedural laws do not empower them to qualify the life sentence with the term “rigorous”.
He said that Chattisgarh High Court has made a violation of Article 21 and 14 of the Constitution.
Today, Supreme Court has agreed to examine the question whether courts are statutorily empowered to make life imprisonments tougher for the convicts by adding “rigorous” to life sentence as the law does not said for the same.