While describing about the creation of man, this book also emphasizes the need of using proper words with each other while the children are playing, joking or simply talking, so that they may avoid creating harsh feelings among others that may lead to quarrels and disputes between them.
Other Sources:
Surah Al-Maa'oon (Chapter 107) from Quran - Arabic English Translation
Surah Al-Maidah (Chapter 5) from Quran - Arabic English Translation
The story of the Jewish Rabbis' lottery about them competing to adopt Maryam