An oblation poured without faith, a gift made to brahmins without faith, austerity practised without faith, and likewise whatever praise, salutation, and the like are done without faith, all of it is called 'asat', the unreal, because it lies outside the path that leads to Me, Partha. Such an act, however much toil it costs, serves neither for fruit hereafter nor for any purpose here, since the good condemn it.

This is a brief sub-gloss. For a fuller reading of this verse, see Madhusūdana, Śaṅkara, or Rāmānuja above.

Even a scriptural oblation and the rest, done without faith, is called 'asat', the unreal. Why? Because that is not, hereafter or here, neither for liberation nor for any transmigratory fruit.

So the supplementary hymns of the Rigveda say, 'sacrifice and the rest, the action done without faith, would be fruitless; the gods call the action that has Him for its aim sad; by the nearness of the words tat and the rest, by the being-pleased of Brahman, and by its having His form, Brahman is brought to bear on it'.