But, by the time he returned on Saturday, Manmohan Singh was completely reinvigorated, serving notice that he was ready to take on the BJP, or for that matter, any other political party - but on his own terms.
The clearest indication of this came during his customary meeting on board his special aircraft while returning home.
"If I were resigning, I won't be here," the prime minister said bluntly.
"The people have elected this government for a five-year term. I hope BJP will respect the verdict and let the parliament function. If they would like to run it their way, that would be a negation of democracy."
Why had he allowed the BJP to set Parliament's agenda with its demand for his resignation stalling Parliament for eight days, he was asked.
"I have to maintain the dignity of the office of the prime minister. I can't get into a tu-tu main-main or a slanging match with other political leaders. So it is better, as I said earlier, that I keep silence."
Manmohan Singh is always firm in his delivery but there is an element of self-effacement whenever he speaks. That was gone on Friday afternoon. Here was a prime minister speaking with a new-found self-confidence, in effect, saying: Enough is enough, now let's move on.
What then happened in those four days in Tehran to bring about the transformation? Plenty!
For one, there was the banquet Iranian President Mahmoud Ahmadinejad hosted for Manmohan Singh Wednesday, a day before the 16th Non-Aligned Movement (NAM) summit opened.
What's so special about that? Well, Manmohan Singh was not on a state visit to Iran. He was only to meet Ahmadinejad and Iranian Supreme Leader Ayatollah Ali Khamenei for bilateral talks on a day when some 60-odd heads of state or government were in Tehran for the summit.
And yet, Ahmadinejad chose to host a banquet for Manmohan Singh - a powerful signal of the esteem he held him in. The import was certainly not lost on the Prime Minister.
Then, Manmohan Singh all but confessed to a virtual spiritual experience during the meeting with Khamenei.
"I was particularly struck by what the Supreme Leader told me about his interest and involvement in Indian affairs. He recalled the influence that Mahatma Gandhi had on him, the role that Jawaharlal Nehru played in India's freedom struggle, his visit to India in 1980-81, meetings with Mrs. Gandhi, visiting various other parts of our country including Hyderabad.
"And what I was more struck by was his statement that a country of India's great diversity, different languages, different religions, has greater chances of achieving its national goals, if there is growing respect for tolerance and respect for diversity. He said that is the way of the future, human civilization is moving in that direction, and what India is trying to achieve is truly remarkable," related Manmohan Singh.
Surely, a breath of fresh air that was - particularly from someone who doesn't really need to wax eloquent about India.
And finally, there was the summit inaugural Thursday. Manmohan Singh was originally scheduled to speak sometime in the afternoon, where his address might have just got lost.
Ahmadinejad ensured that didn't happen, juggling the list to ensure Manmohan Singh was among the earliest speakers. Finally, the prime minister was at centre stage in his own right - an economist and a statesman. He was among leaders whose mindset was far removed from the West and who did not just see the world in black and white but in the in-betweens that were equally important.
At the same time, there were no tangibles from the visit - a bland agreement to improve the trade balance that is tilted against India, no movements on the manner of India's oil imports and no agreement on the price of gas to be carried by a pipeline from Iran to India through Pakistan.
But for once, the intangibles seem to have overtaken the tangibles and Manmohan Singh had seized the moment.
Tehran/New Delhi: He left on Tuesday as an embattled prime minister with the Bharatiya Janata Party (BJP) baying for his blood over the presumptive loss to the nation in alleged irregularity in the award of lucrative coal mining blocks.
First Published: Saturday, September 01, 2012, 13:33