Virtue of freeing Slaves

In the Musnad, there is a Hadith from Al-Bara' bin `Azib that a man asked, "O Allah's Messenger! Direct me to an action that draws me closer to Paradise and away from the Fire.'' The Messenger of Allah said,

« أَعْتِقِ النَّسَمَةَ وَفُكَّ الرَّقَبَة »

(Emancipate the person and free the neck (slave).) The man asked, "O Allah's Messenger! Are they not one and the same'' He said,

« لَا، عِتْقُ النَّسَمَةِ أَنْ تُفْرِدَ بِعِتْقِهَا، وَفَكُّ الرَّقَبَةِ أَنْ تُعِينَ فِي ثَمَنِهَا »

(No, you emancipate a person by freeing him on your own, but you untie a neck (slave) by helping in its price.)