sarvottama bhajana ei sarva-bhakti jini'
ataeva krsna kahe,--'ami tomara rni'
sarva-uttama—above all; bhajana—devotional service; ei—this; sarva-bhakti—all types of bhakti; jini'-conquering; ataeva—therefore; krsna kahe—Lord Krsna says; ami—I; tomara—your; rni—debtor.
"The conjugal love of the gopis is the most exalted devotional service, surpassing all other methods of bhakti. Therefore Lord Krsna is obliged to say, 'My dear gopis, I cannot repay you. Indeed, I am always indebted to you.'
Link to this page: http://prabhupadabooks.com/cc/antya/7/43