וְגַ֣ם׀ אֲנִ֣י שָׁמַ֗עְתִּי אֶֽת־נַאֲקַת֙ בְּנֵ֣י יִשְׂרָאֵ֔ל אֲשֶׁ֥ר מִצְרַ֖יִם מַעֲבִדִ֣ים אֹתָ֑ם
So which is it -- was Hashem moved by the cries of Bnei Yisrael, in which case אֲשֶׁ֥ר מִצְרַ֖יִם מַעֲבִדִ֣ים אֹתָ֑ם is extraneous, or was Hashem moved by the injustice of the Egyptian persecution, irrespective of whether anyone else cried out or objected to it, in which case אֶֽת־נַאֲקַת֙ בְּנֵ֣י יִשְׂרָאֵ֔ל is extraneous?
The Oheiv Yisrael (also R' Liebele Eiger) explains the pasuk as follows: many people go through life ho-hum without thinking too much about G-d, until one day when the going gets tough, and then suddenly its time to break open the Tehillim and rediscover what avodas Hashem means. Klal Yisrael in Egypt was pushed until their backs were against the wall, and so they cried out to Hashem for help. But what they cried about is more than the pain of slavery. What they cried about is the fact that it took a crisis to bring them to that point. They cried because אֲשֶׁ֥ר מִצְרַ֖יִם מַעֲבִדִ֣ים אֹתָ֑ם -- the Egyptians were the ones that drove them to avodas Hashem. It shouldn't take a crisis to bring the children of Avraham, Yitzchak, and Yaakov to speak to their Father upstairs.