The fourth Sukta from the first mandala of the Rigveda is dedicated to Devraj Indra. His sage is Madhuchchhanda. The verses used in these are Gayatri. Here is a compilation of total 10 mantras which are given below with their explanation.
सुरुपकृत्नुमतये सुदुघामिव गोदुहे । जुहूमसि द्यविद्यवि ॥ 1 ॥
Sages say – Just as cows are called for the exploitation of milk, in the same way we invoke the best Yagyakarma Indra for our protection.
उप नः सवना गहि सोमस्य सोमपाः पिब । गोदा इद् रेवतो मदः ॥ 2 ॥
Through this mantra, Rishi Indra is demanding cow wealth from God. They say – Hey Sompayee Indra! You come to our yagya to drink Som and after taking Som, being happy, give cows etc. money to us petitioners.
अथा ते अन्तमानां विद्याम सुमतीनाम्। मा नो अतिख्य आ गहि ॥ 3 ॥
Sage says – Hey Indra! May we gain more and more knowledge about you by being in the presence of the best wise men who are closer to you. You also don’t reveal your form in front of anyone other than us.
परेहि विग्रमस्तृतमिन्द्रं पृच्छा विपश्चितम्। यस्ते सखिभ्य आवरम् ॥4॥
Sage says – O wise man! You go near Indra, the undefeated, executive, with special intelligence and get wealth and prosperity for the sake of friends and relatives.
उत ब्रुवन्तु नो निदो निरन्यतश्चिदारत। दधाना इन्द्र इद् दुवः || 5 ||
Rishis say – Those who worship Indra should ask those who criticize him (Indra) to go away, so that they may run away from the country as well.
उत नः सुभगां अरिवचेयुर्दस्म कृष्टयः । स्यामेदिन्द्रस्य शर्मणि ॥ 6 ॥
Sage says – O Indra by your grace! May we get all the glory etc., so that whatever enemy or friend sees us, they consider us fortunate. Emashumashve bhar yagyaashriya nrimadanam.
एमाशुमाशवे भर यज्ञश्रियं नृमादनम् । पतयन् मन्दयत्सखम् ॥ 7 ॥
Sage say – dedicate Som to the fast-moving Indra who beautifies the Yagya, gives joy, gives happiness, completes the Yagya and makes the relatives happy.
अस्य पीत्वा शतक्रतो घनो वृत्राणामभवः । प्रावो वाजेषु वाजिनम् ॥ 8 ॥
Sage says – O Indra who performs hundreds of Yagya! You have become the destroyer of the demons by becoming strong with this som leaf. With this power, you are the protector of the warriors in the battlefield.
तं त्वा वाजेषु वाजिनं वाजयामः शतक्रतो । धनानमिन्द्र सातये ॥ 9 ॥
Sage says – O Shatkarma Indra! To you who gives strength in wars, we dedicate Havishyanna for the attainment of wealth and opulence.
यो रायो वनिर्महान्त् सुपारः सुन्वतः सखा । तस्मा इन्द्राय गायत ॥ 10 ॥
Sage says – the one who is the protector of wealth everywhere, the destroyer of troubles and the one who has a sense of friendship with Yagyikas, sing hymns to that Indra.
Note – If the fourth hymn of the first circle is read carefully, then it can be understood that their sage is only Madhuchchhanda and here all the mantras are dedicated to Indra. We can probably assume that Rishi Madhuchchhanda must have been the foremost worshiper of Devraj Indra.