The famous Sri Vaishnava Acharya Ramanujacharya had 74 disciples, known as the Simhasanadhipatis, but three of his closest disciples were Kurathalwan, Mudhaliandan, and Vaduga Nambi. Kurathalwan is the one who got his eyes plucked out by the Shaivite Chola king as I discuss here. Mudhaliandan was Ramanujacharya's sister's son and the temple administrator of Sri Rangam (as well as my ancestor). Vaduga Nambi was an atheist whom Ramanujacharya converted to Sri Vaishnavism in Karnataka, and he got the rare blessing of preparing Ramanujacharya's milk on a daily basis.
Now the 13th century Sri Vaishnava Acharya Pillai Lokacharya makes an interesting statement about these three disciples in verse 411 of his Sri Vachana Bhushanam:
Vaduga Nambi Azhvanaiyum Andanaiyum Irukaraiyarenbar
Vaduga Nambi says that Alvan and Andan are double-minded men.
Here's what the translator says:
Alwan and Andan (Kurathalwan and Mudhaliandan), disciples of Ramanuja, would sometimes seek out the Lord and at other times seek their Acharya.
So it seems that Vaduga Nambi said that Kurathalwan and Mudhaliandan are double-minded because they would sometimes seek refuge in the lotus feet of Vishnu and other times seek refuge in the lotus feet of Ramanujacharya, whereas Vaduga Nambi exclusively sought refuge in the lotus feet of Ramanujacharya. That was the depth of Vaduga Nambi's Acharya Bhakti; there's a famous incident where the Ranganatha statue passed by Vaduga Nambi's house, but Vaduga Nambi didn't even go outside to see it because he was busy boiling milk for Ramanujacharya.
But my question is, where does Vaduga Nambi say this? Does he say this in one of his works? I know of two works by Vaduga Nambi: the Yatiraja Vaibhavam, a poem summarizing Ramanujacharya's life, and the Ramanuja Ashtotthara Satanamam, a hymn listing 108 names of Ramanujacharya. The Yatiraja Vaibhavam is available in English here, but I can't seem to find the Ramanuja Ashtotthara Satanamam.
Or could it have been a statement Vaduga Nambi said out loud to someone, and was passed down by oral tradition? Many sayings of Sri Vaishnava Acharyas have been passed down by oral tradition.