There is a detailed description of this Sign on page 5231 of Barahin-e-Ahmadiyya. The sum and substance of it is that once I received the revelation:
Twenty and one rupees are coming.
So this revelation, too, was communicated to the Aryas whose names have been mentioned above a number of times. With the revelation, I was given to understand that the money would arrive the same day. Thus, one Wazir Singh, a patient, came and gave me one rupee that day. Then it occurred to me that perhaps the remaining twenty rupees would come by post. Therefore, a reliable person was sent to the Post Office who reported that the postal clerk said he had only received five rupees from Dera Ghazi Khan, accompanied by a postcard. I was very perplexed by this news, for I had already informed the Aryas that I would receive twenty-one rupees on that day. They knew one rupee had already come. I was so distressed by the postal clerk’s report that cannot be described in words, since the news that only five rupees had been received from Dera Ghazi Khan had made me lose all hope of receiving additional money. There were indications that the Aryas who were privy to the earlier report, were ecstatic that they were finally given a chance to prove me wrong that day. I was in extreme distress. Then suddenly I received the revelation
Twenty and one have arrived; there is no doubt in this.
I communicated this revelation to the Aryas only to cause even greater laughter, for a government employee who was the sub-postmaster had publicly announced that only five rupees had come. After this, one from among those Aryas happened to visit the Post Office. The postal clerk on inquiry or on his own, told him, ‘In fact, twenty rupees have been received; I had just inadvertently blurted out that only five rupees had been received.’
Accompanying it there was also a postcard from Munshi Ilahi Bakhsh, Accountant. This sum had arrived on 6 September 1883 exactly the day I received the revelation. In commemoration of this auspicious day and to make the Aryas bear witness to it, sweets worth one rupee was distributed which was fetched by an Aryah and it was given to the Aryas and others so that, if not otherwise, they should remember the occasion by eating sweets.
1 This Sign appears in Ruhani Khaza’in, vol. 1, page 624, published in 2008. [Publisher]