This story (Thiththira Jathaka) was told by the Buddha in order to teach that respect must be paid to age, that is, to senior & elders.
Once upon a time, under a great banyan-tree on the slopes of the Himalayas, there dwelt three friends, a partridge, a monkey, and an elephant. And they came to lack respect and subordination one to another and had no ordering of their common life. And the thought came to them that it was not seemly for them to live in this way and that they ought to find out which of their number was the senior and to honour him.
As they were engaged thinking which was the oldest, one day an idea struck them. Partridge and the monkey said to the elephant as they all three sat together at the foot of that banyan-tree, “Friend elephant! How big was this banyan tree when you remember it first?” The elephant said, “When I was a baby this banyan tree was a mere bush, over which I used to walk; I’ve known the tree since it was a mere bush.”
Next, the monkey was asked the same question by the other two; and he replied, “My friends! when I was a young, I had only to stretch out my neck as I sat on the ground, and I could eat the topmost sprouts of this banyan. So I have known this banyan since it was very tiny.”
Then the partridge was asked the same question by the two others; and he said, “Friends! Two miles away there is a banyan-tree; I ate its seeds, and voided them here; that was the origin of this tree. Therefore, I have knowledge of this tree from before it was born, and am older than the pair of you.”
The monkey and the elephant said to the partridge, “Friend! you are the oldest. Hence you shall have from us acts of honour and veneration, marks of obeisance and homage, respect of word and deed, salutation, and all due homage; and we will follow your counsels. You for your part hence will please impart such counsel as we need.”
Then onwards the partridge gave them counsel and established them in the Commandments, which he also undertook himself to keep. Being thus established in the Commandments, and becoming respectful and subordinate among themselves, with the proper ordering of their common life, these three made themselves sure of rebirth in heaven at this life’s close.
Master said: “That to seniority shall be paid respect of word and deed, salutation, and all due service; that seniority shall be the title to the best lodging, the best water, and the best price; and nevermore let a senior be kept out of lodging by a junior. Whosoever so keeps out his senior commits an offence.”
It was at the close of this lesson that the Master, asl Buddha, said:
For they who honour age, in Truth are versed;
Praise now, and bliss hereafter, is their meed.