The Affection of the Prophet Towards His Ummah
Aishah (radi Allahu anha) reported that the Messenger of Allah (sal Allahu alaihi wa sallam) would sometimes abstain from doing something he wished to do, lest others should follow him and it might become obligatory upon them.
[Sahih al-Bukhari and Muslim]
This Hadith indicates the affection which the Prophet (sal Allahu alaihi wa sallam) had for his followers. In spite of his fervent desire, he would sometimes deliberately leave voluntary prayer lest it became obligatory upon the Muslims.
And Allah Knows Best!