He cannot go back on His promise to his beloved devotees.

भवद्भक्तिः स्फीता भवतु मम सैव प्रशमयेद्
अशेषक्ळेसौघं न खलु हृदि सन्देहकणिका।
न चेद् व्यासोक्तिस्तव च वचनं नैगमवचो
भवेन्मिथ्या रथ्यापुरुषवचनप्रायमखिलं॥५॥
श्रीमन्नारयणीयं दशकं ३
bhavadbhaktiḥ sphītā bhavatu mama saiva praśamayed
aśeṣakḻesaughaṁ na khalu hṛdi sandehakaṇikā|
na ced vyāsoktistava ca vacanaṁ naigamavaco
bhavenmithyā rathyāpuruṣavacanaprāyamakhilaṁ||5||
śrīmannārayaṇīyaṁ daśakaṁ 3

Now the scholar and the devotee in Bhattathiripad work together.   The scholar applies logic to the emotional quantum of devotional love for the Lord. 
"My Guruvaayurappa, I want only the absolute and unwavering devotion and love for you may blossom in my heart.  There is not even an iota of doubt in my heart that such devotion will annihilate  even the smallest physical discomfiture of body and mind that afflicts me.   If this belief is not true, the words uttered by Vedas, Yourself and Vyasa on various occasions should becaome false like the bombastic announcements made by some unknown rascal without any identity just roaming around the streets.   "
The words of Vyasa recorded in Bhagavatam  and in Vedas definitely  assure us that the follower of the Lord can come to not grief. "Na me bhakthaH pranasyati.. my devptee will never come to harm..Gita.  TadvishnoH paramam padam, sadaa pashyanthi suurayaH...all the wise me look for to the exalted feet of Vishnu for welfare here and hereafter.. Vedas/ The promises of the Lord are many.  He cannot go back on His promise to his beloved devotees.

--

।श्रीकृष्णो रक्षतु।
|śrīkṛṣṇo rakṣatu|
Have a nice and happy day
with profound respect and warm regards
K V Ananthanarayanan
blog   http://kanfusion.blogspot.com/
त्यजन्तु बान्धवाः सर्वे निन्दन्तु गुरवो जनाःI
तदापि परमानन्दो गोविन्दो मम जीवनंII
let all my relatives abandon me, let the great people insult me, still I am in supreme bliss since my life  is GOVINDA alone.
Iकृष्णात् परं किमपि तत्वं अहं न जाने"I
लोकाः समस्ताः सुखिनो भवन्तु।
lokāḥ samastāḥ sukhino bhavantu|