The Torah commands us to eat on Erev Yom Kippur. This not only gives us the strength to fast, but also provides a way of honoring Yom Kippur with food and drink. Many tzaddikim who would usually use only one hand when eating, would use both hands when eating on Erev Yom Kippur.
(שו"ע אדה"ז סי' תרד, לקו"ש חכ"ט ע' 319)
One Erev Yom Kippur, a Roman officer dispatched his servant to buy him a fish. At the market he found only one fish on sale and agreed to pay one gold coin for it. However, a Yiddishe tailor who was standing there approached the seller and offered a higher bid. He and the servant tried to outbid each other, until the Yid won the fish for the sum of five gold coins. When the officer was told what had happened, he was understandably upset – but also curious.
He sent for the Yid and asked him: “Why did you spend five coins on a fish and not let my servant buy it?”
The Yiddishe tailor answered, “How could I not have bought it, even if it had cost ten gold coins? I bought it to eat on a day on which Hashem commanded us to eat and drink, a day when we are certain that He will forgive our sins.”
The officer was so impressed that he sent him off in peace.
(טור או"ח סי' תרד)
On Erev Yom Kippur, תרמ”ט (1888), a vintage chossid called Reb Zalman of Tcherbin walked right into the Rebbe Rashab’s study after shachris and greeted him with a jovial “Gut Yom Tov!”
The Rebbe Rashab, who was seriously engrossed in a sefer, replied, “Yes, it is Yom-Tov, and Yom-Tov is a time to be happy. But it is also Erev Yom Kippur, and one must be in a state of hisorerus teshuvah (arousal to teshuvah) from the depths of one’s heart. And teshuvah consists of regret over the past and undertaking positive resolutions for the future.”
Reb Zalman responded, “Rebbe, we are soldiers. Hashem told us that the first half of Erev Yom Kippur is a Yom-Tov, so we need to be joyful. Only after chatzos must one daven minchah, say Al Cheit, and do teshuvah.”
And he concluded by saying, “Rebbe, give me lekach.” The Rebbe Rashab, pleased with his answer, took a piece of honey cake from the plate and said, “I am giving you a piece of lekach, and may Hashem give you a sweet year.”
(סה"ש קיץ הש"ת ע' 10)