((كَانَ النَّبيُّ صلى الله عليه وسلم إِذَا أَتَاهُ أَمْرٌ يَسُرُّهُ أَوْ يُسَرُّ بِهِ خَرَّ سَاجِداً شُكْراً لِلَّهِ تَبَارَكَ وَتَعَالَى)).
(The Prophet PBUH would prostrate in gratitude to Allah upon receiving news which pleased him or which caused pleasure. )
Abu Dawud, Ibn Majah, At-Tirmidhi. See also Al-Albani, Sahih Ibn Majah 1/233, and 'Irwa'ul-Ghalil 2/226.