Shama-il Tirmidhi Chapter 029, Hadith Number 002 (189).

Aisha radiyallah anha reports that, Rasoolullah sallallahu alaihe wasallam ate watermelon with fresh dates.

Commentary
In Tirmidhi and other narrations, in explaining this, Sayyidina Rasoolullah sallallahu alaihe wasallam also said, The cold effect of one removes the heat of the other, and the heat of one removes the cold effect of the other.