A Bunch of Old Letters – Written mostly to Jawaharlal Nehru and some written by him. First British Edition, 1960, Asia Publishing House, pp. 187-188
http://www.koranselskab.dk/profiler/iqbal/ahmadiyya.htm

Lahore, June 21, 1936
My dear Pandit Jawaharlal,

Thank you so much for your letter which I received yesterday. At the time I wrote in reply to your articles I believed that you had no idea of the political attitude of the Ahmadis.1 Indeed the main reason why I wrote a reply was to show, especially to you, how Muslim loyalty had originated and how eventually it had found a revelational basis in Ahmadism.

After the publication of my paper I discovered, to my great surprise, that even the educated Muslims had no idea of the historical causes which had shaped the teachings of Ahmadism.

Moreover your Muslim admirers in the Punjab and elsewhere felt perturbed over your articles as they thought you were in sympathy with Ahmadiyya movement. This was mainly due to the fact that the Ahmadis were jubilant over your articles. The Ahmadis Press was mainly responsible for this misunderstanding about you. However I am glad to know that my impression was erroneous.

I myself have little interest in theology, but had to dabble in it a bit in order to meet the Ahmadis on their own ground. I assure you that my Paper was written with the best of intentions for Islam and India. I have no doubt in my mind that the Ahmadis are traitors both to Islam and to India.

I was extremely sorry to miss the opportunity of meeting you in Lahore. I was very ill in those days and could not leave my rooms. For the last two years I have been living a life of practically of retirement on account of continued illness. Do let me know when you come to the Punjab next.

Did you receive my letter regarding your proposed Union for Civil Liberties? As you do not acknowledge it in your letter I fear it never reached you.

Yours sincerely,

Mohammad Iqbal