Bhishma’s Advaitic realization

In the Srimad Bhagavatam, 1st Canto, Chapter 9, Bhishma, in his last moments, does a stuti of Sri Krishna and finally says:

तमिममहमजं शरीरभाजांहृदि हृदि धिष्ठितमात्मकल्पितानाम् ।प्रतिद‍ृशमिव  नैकधार्कमेकंसमधिगतोऽस्मि विधूतभेदमोह: ॥ ४२ ॥
I have realized that Supreme who is present in each and every manas of the beings which Brahman has created. It is akin to one sun appearing as many in the various reflecting bodies. So too One Atman alone exists and the perception of apparent multiplicity is due to delusion, from which I am now free.
The delusion, ‘bheda moha’, is stated in the Vishnu Purana too:
सर्वभूतान्यभेदेन ददृशे स तदात्मनः ।यथा ब्रह्मपरो मुक्तिमवाप परमां द्विजः ॥ २,१६.२० ॥तथा त्वमपि धर्मज्ञ तुल्यात्मरिपुबान्धवः ।भव सर्गगतं जानन्नात्मानमवनीपते ॥ २,१६.२१ ॥सितनीलादिभेदेन यथैकं दृश्यते नभः ।भ्रान्तदृष्टिभिरात्मापि तथैकः सन्पृथक्पृथक् ॥ २,१६.२२ ॥एकः समस्तं यदिहास्ति किञ्चित्तदच्युतो नास्ति परं ततोन्यत् ।सोऽहं स च त्वं च सर्वमेतदात्मस्वरूपं त्यज भेदमोहम् ॥ २,१६.२३ ॥
‘Just as that Brahmana attained liberation owing to his perceiving everything as non-different from the Self, thereby tuned to Brahman, you too, O King, knower of Dharma, looking upon yourself, enemies and relatives as the same, knowing the One Atman to be present in all. The wrong perception of many Atmans is due to delusion, as exemplified in the space/sky appearing as many owing to the erroneous perception of colors such as white, black, etc. even though space is one only without any colors. Whatever exists is only that Supreme Achyuta and nothing else other than That exists. All perception of duality as ‘I am that, you are that, he is’ etc. are all due to  ignorance which you give up. 
We may recall the Bhashya of Shankaracharya to the Bh.Gita 2.12 where he says:  The plural used in the verse to refer to the various entities in the battle is due to the plurality in the bodies and not due to the plurality of Atman.  We find validation of Shankara’s remark in the Bhagavatam and the Vishnu Puranam cited above.
न त्वेवाहं जातु नासं न त्वं नेमे जनाधिपाः ।न चैव न भविष्यामः सर्वे वयमतः परम् ॥ १२ ॥ 2.12.न तु एव जातु कदाचित् अहं नासम् , किं तु आसमेव । अतीतेषु देहोत्पत्तिविनाशेषु घटादिषु वियदिव नित्य एव अहमासमित्यभिप्रायः । तथा न त्वं न आसीः, किं तु आसीरेव । तथा न इमे जनाधिपाः न आसन् , किं तु आसन्नेव । तथा न च एव न भविष्यामः, किं तु भविष्याम एव, सर्वे वयम् अतः अस्मात् देहविनाशात् परम् उत्तरकाले अपि । त्रिष्वपि कालेषु नित्या आत्मस्वरूपेण इत्यर्थः । देहभेदानुवृत्त्या बहुवचनम् , नात्मभेदाभिप्रायेण ॥ १२ ॥

Sridhara Swamin’s commentary to the Bhagavatam verse:

The commentary highlights the idea of delusion behind plurality of Atman, on the analogy of the one sun reflecting in the various water bodies. 

Om Tat Sat