This sounds very much like the story of Cūḷapanthaka who was a monk, but had in fact some sort of learning disability. The other monks, including his brother, just told him he can’t do the practice and wanted to send him back home, away from the monastery. But the Buddha saw that differently.
Here are his verses from the Theragatha:
Verses of the Senior Monks
The Book of the Tens
My progress was slow,
I was despised in the past.
Even my brother turned me away,
saying, “Go home now.”
Turned away at the gate
of the Saṅgha’s monastery,
I stood there sadly,
longing for the dispensation.
Then the Buddha came
and touched my head.
Taking me by the arm,
he brought me into the Saṅgha’s monastery.
The Teacher, out of compassion,
gave me a foot-wiping cloth, saying:
“Focus your awareness
exclusively on this clean cloth.”
After hearing his words,
I happily did his bidding.
I practiced meditative immersion
for the attainment of the highest goal.
I know my past lives,
my clairvoyance is clarified;
I’ve attained the three knowledges,
and fulfilled the Buddha’s instructions.
I, Panthaka, created a thousand
images of myself,
and sat in the delightful mango grove
until the time for the meal offering was announced.
Then the teacher sent to me
a messenger to announce the time.
When the time was announced,
I flew to him through the air.
I paid homage at the teacher’s feet,
and sat to one side.
When he knew I was seated,
the teacher received the offering.
Recipient of gifts from the whole world,
receiver of sacrifices,
field of merit for humanity,
he received the religious donation.