In the Thirumantiram, tenth volume of 12 volumes of Tirumurai, Thirumoolar mentions among those that pleases Lord Shiva. Thirumoolar is one of the 18 Siddhars and also one among the 63 Nayanars.
Yaavarkumaam Iraivanuku Oru Pachillai
Yaavarkumaam Pasuvuku Oru Vaayurai
Yaavarkumaam Unnumpothu Oru Kaipidi
Yaavarkumaam Piraruku Innurai Thanei
(From Mudhal than^thiram (First Tantra) paththAm thirumuRai (tenth Tirumurai))
English Translation:
Even using just a leaf like Bilva to worship daily
Feeding a mouthful to a cow
A handful of food for someone else while eating
A comforting word to someone else
A comforting and pleasing speech pleases Lord Shiva.