When Duryodhana performed prapatti to balarAma, it was weakened by his dependence on bhIShma and others.
Thus, in order to ensure duryodhana's sharaNAgati was strengthened and he attained sat-gati, it was nArada who became his AchArya, as follows+
शिष्ययोर्यदि - "Though you favor duryodhana, remember that bhIma is also to be protected by you".
nArada knew the danger bhIma was in due to the surrender of duryodhana, and hence became bhIma's AchArya too, to ensure the latter achieved his objective+
अहं हि सर्वदा स्तौमि नारदं देवदर्शनम् (~ skanda purANa)
[Krishna - "I myself am ever praising Narada, who has a clear vision of the supreme god (myself)"]
Krishna himself composed a stuti on Narada. Might translate it when time permits, to explain what makes him so great.
There is this shloka in Linga Purana:
रुद्रेण नीलरुद्रेण श्रीसूक्तेन शुभेन च ।
रजनीसूक्तकेनैव चमकेन शुभेन च ॥
[(One worships the Shiva Linga) through recitation of the Rudram, the Nilarudra Sukta, the most auspicious puruSha sUkta, the rAtri (rajanI) sUkta and the Chamaka]+
Thus, this sequence of sAdhana is hinted by the order in which the sUktAs are recited while worshipping the shiva-linga that represents the jIvAtma.
Even the tAmasIka purANAs acknowledge and promote this tattva+


