Reference for Dayanand Saraswati rejecting Brahmanas of Vedas and Aranyakas-
The ref. can be found in his work Rigvedaadi Bhasya Bhumika - Chapter VI - Definition of the Vedas. Page no. 34-38. Below are excerpts from the book.
Dayananda was the first among the modern scholars to state that the Samhitas only formed the Vedas and they alone were to be regarded as eternal, and infallible, as Vedas in fact. The Brahmanas and Upanisads themselves profess to be mere parasites of the Vedas and devote themselves respectively to the elucidation of the ritualistic and tbe philosophical portions of the Vedas. No Samhita , on the other hand, professes to hang upon any other Samhita as its parasite and devote itself to explain any portion of the others.
Dayananda says :
The Brahmnas as do not deserve to be called by the name of the Veda
because they have been given the names of the Purana)a and Itihiisa ;
they are elucidations of the Vedas and are not the words of God but
merely the works of tbe seers and the products of human intellect ;
also because all sages other than Kiityayana have refused to call them
by the name of Veda.
DIFFERENCE BETWEEN SAMHITAS AND BRAHMANAS
This is quite true that there are no stories in the Vedas. The Brahmnas as do contain narratives of human beings, while the Vedas are free from stories and tales.
Moreover, the Brahmas are the explanatory books on the Vedas. Here
the Vedic stanzas are repeated and explained later on. Hence the
Brahmanas are the glosses on the Vedas, How can commentary be given
the same position as the original one.
The very title of these books, i.e. Brahmana, indicates that these works are not the Vedas. Brahma means here Veda and their explanatory books are called Brahmanas. The following instances may again prove it .
As the Brahmanas are man-made works, they contain criticism of other similar works. Sometimes they contain statements contradictory to each other. ' It clearly shows that they cannot be given title title of the Veda.
The accent plays essential part in the language of the Vedas while the same is lacking in the Brahmanas.
Moreover, the four Vedas are the revealed books ; they are words' of God ; but the Brahmanas are human creation and were composed by sages.