The story of Sri Krishna, Yudhishtira and the bitter gourd

Question

Is there any scriptural basis to this story of Sri Krishna, Yudhishtira and the bitter gourd?

The story goes like this:

After the Mahabharata war, King Yudhishtira and his brothers decide to go on a pilgrimage to cleanse themselves of sins committed during the war. Yudhishtira requests Sri Krishna to accompany them on their voyage. Krishna obliges but instead of accompanying himself, sends a bitter gourd in his place, telling Yudhishtira to treat the bitter gourd as (Krishna) himself, dip it in the holy waters and bring it back to him.

Yudhishtira doesn't question or doubt Krishna's reasons and does as advised. He dips the bitter melon in the sacred waters at all holy places he visits and brings it back to Krishna. Krishna then cuts the bitter melon and serves it to all the Pandavas and asks them to eat it. The Pandavas don't seem too happy chewing it down their throats as the gourd was still bitter. They complain. Krishna then offers them some wisdom, that just as the bitter gourd took dips in holy water and still remained bitter as ever, so do your sins. It's a mere whim that you can wash away your sins by going on a pilgrimage or immersing in holy water.

Moral of the story:

You cannot wash away your sins by simply dipping yourself in river Ganga or any sacred waters.

Answer 1

There is no such story about Paandavas going for pilgrimage without Krishna for washing their sins long after the war was over.

The story is exactly reverse. It was lord Krishna who advised Paandavas to perform a sacred ritual which was supposedly done after the war. It can be seen in this video of Ramanand Sagar's Krishna, which was more compliant with the scriptural texts.

Also it can be found in the Shalya Parva after defeating Duryodhana:

Then Vasudeva of great renown said, 'We should, as an initiatory act of blessedness, remain out of the camp for this night.' Answering, 'So be it!' the Pandavas and Satyaki, accompanied by Vasudeva, went out of the camp for the sake of doing that which was regarded as an auspicious act. Arrived on the banks of the sacred stream Oghavati, O king, the Pandavas, reft of foes, took up their quarters there for that night!

However, yes the moral message is true which you got. When Paandavas were away, Ashwatthama killed the whole remaining army including their sons. Something which was terrible for them.

The other instance where Krishna suggests a kind of Pilgrimage is to Yaadavas. However we all know that, while being in Prabhas for such "sin-washing" activity, the Yaadavas got involved into "sinful" activities and ended up killing each other. It can be found in Mausala Parva:

Krishna gets concerned, asks everyone to go on a pilgrimage to the sacred waters of the Prabhas sea. They do. When they arrive, the Yadavas revel in merry making, dance and drink lots of alcohol.

Personally, I would refrain from such anti-Paandava stories, not because I have any prejudice against Kaurava. But sometimes, there is a conscious trend to demean them.