Srimad Bhagavatam Canto 06, Chapter 09, Text 08

SB 6.9.8

turyam cheda-virohena
 varena jagrhur drumah
tesam niryasa-rupena
 brahma-hatya pradrsyate
 
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
In return for Indra’s benediction that their branches and twigs would grow back when trimmed, the trees accepted one fourth of the reactions for killing a brahmana. These reactions are visible in the flowing of sap from trees. [Therefore one is forbidden to drink this sap.]
Srimad Bhagavatam Canto 06, Chapter 09, Text 07
Srimad Bhagavatam Canto 06, Chapter 09, Text 09